Notes on “C” Programming
Basic Model of Computation
To solve any kind of problem we need to write a step-by-step process of solution using simple
instruction to obtain the result. There would be numbers of methods to solve a problem and solution may
differ from person to person.
Example: If you have to inform a person with a distance of 10 KM then how will you do it?
Person 1: Tele Calling to him
Person 2: Messaging to him
Person 3: Physical visit to him
And so on…..
The Basic Steps of Computation:
a. Formulating the Problem and decide the data-types to be input.
b. Identifying the step of computation that is necessary for getting the solution.
c. Identifying the decision point, under what circumstances a particular operation to be performed
and when not to be performed.
d. Knowing the expected results and verifying with the actual values.
Procedure for Problem Solving
To solve a problem first we have to break down the problem into small parts which can be solved
step by step to arrive at the final solution. It need not involve the computer. Every problem is unique by
itself, but some steps are common. They are as follows…
1. Spend some time to understand the problem thoroughly. In this step we do not need a computer.
We need to try to answer what is expected & how to get it.
2. Construct a list of variables that are needed to get the solution of the problem.
3. Decide the layout for the output presentation.
4. Select the programming technique which is best suited to solve the problem. Then carryout a
coding using a programming language.
5. Test the Program. In this step we test the each part of the program whether it is functioning
properly or not.
6. Validation of the program. This step guards the program against wrong data processing. Here we
check the program by input wrong data to it. If wrong data is processed then there is an error else
program is correct.
Algorithms
It is a set of instruction which describe the steps to be followed to carry out an activity. If it is
written in the computer programming language then it is called a program. It tells us how to go about for
getting the solution of a problem.
Example:
Making a cup of Tea
1. Begin
2. Take the suspense
3. Turn on The Gas
4. Put ignition to the Gas
5. Add some water in the suspense
6. Add some tea powder & Sugar
7. Boil it upto 5 min
8. Turn off the Gas
9. Filter the Tea
10. Serve it into the cup
11. End
Identify whether a number is odd or even
1. Begin
2. Input a Number (Read a No)
3. Divide the Number by 2
4. If the remainder is 0, then No is even
5. Else The No is Odd
6. End
Calculate the Total of serial no upto 9
1. Begin
2. Read a number 9
3. Take a variable x and assign 1 to it
4. Take another variable as sum
5. Add the value of x to sum
6. Add 1 to x
7. check if x>=9 then display the value of sum
8. else repeat the step 5 & 6
9. end
Flow Chart
A Flow chart is a graphical representation of the sequence of operations for the solution of a
problem. Flow chart shows the sequence of instruction written in a single program or subroutine.
It uses boxes and lines of different shapes to denote different types of instructions. The instructions
are written in these boxes in clear and concise manner. These boxes are connected with solid lines with
arrow head, these lines are called flow line. It denotes the flow or actual sequence of the program. Though
the flow chart shows a program in a graphical form, logical errors can be detected very easily.
Once a flowchart is ready, the making a programming code in any programming language becomes
very easy.
Flow Chart Symbols
Terminal: - It is used to indicate the Starting (Begin) or Ending (End) of a Program. It is
the first symbol & also the last symbol in the flowchart.
Input / Output: - It is used to indicate the operation of input and output of the
program. If there is a program input from a Disk, CD, Pen Drive or any other input devices
then that step will be indicated in this box. Also an output to display on the monitor is also
represented here.
Processing: - it is used to represent the process of a program. An arithmetic instruction,
Data movement in a program, addition, subtraction, multiplication, division type operational
instructions are represented here.
Flow Lines: - A Line with arrow head is called flow line which is used to indicate the
sequential flow of instruction in a program. These flow lines indicates a data flow of left to
right, right to left and top to bottom only. Bottom to top flow line is not used in flow chart.
Decision box: - It is also called as Diamond box. It is used to indicate a point at which a
decision has to be made and to branch to one of the alternatives.
Connectors: - If a flow chart becomes long and the flow lines got crisscross the it need
another area or paper to make a prefect flowchart. To join these two area or paper we need
connector. A circle connector is used to connect two part of a program written in a single
paper. A pentagon shape is used to connect two part of a program written in two different
papers.
Predefined Process (Function):- Used to represent a group of statements performing
one processing task.
Algorithm to Identify smallest number among 7 numbers
12,5,8,14,17,34,3
1. Start
2. Take 7 variables a,b,c,d,e,f,g.
3. Read the 7 variables
4. Compare a < b, if true
5. Compare a < c if true
6. Compare a < d if true
7. Compare a < e if true
8. Compare a < f if true
9. Compare a < g if true
10. a is smallest
11. else compare b < c if true
12. Compare b < d if true
13. Compare b < e if true
14. Compare b < f if true
15. Compare b < g if true
16. b is smallest
17. else compare c < d if true
so on …..
30. compare f < g
31. f is smallest
32.Else g is smallest
Algorithm to Check multiple of a number
1. Start
2. Take variables x, n & count
3. Read the variable x, n as 0 & count as 0
4. Check x > n, if true
5. Add 1 to n
6. Divide x by n
7. Check x is divisible by n, if true
8. Add 1 to count
9. Repeat the step 4, 5, 6 & 7
10. If false, repeat the step 4, 5, 6 & 7
11. If false, display Count
12. end
Algorithm to check whether No is Prime or Not
1. Start
2. Take variables x, n & count
3. Read the variable x, n as 0 & count as 0
4. Check x > n, if true
5. Add 1 to n
6. Divide x by n
7. Check x is divisible by n, if true
8. Add 1 to count
9. Repeat the step 4, 5, 6 & 7
10. If false, repeat the step 4, 5, 6 & 7
11. If false,
12. Check count<= 2, if true
13. The No is Prime
14. If false, The no is Not Prime
15. end
Symbols Used in C Programming
; Semi Colon
. Dot
, Coma
: Colon
“ Double Quotes
‘ Single Quotes
! Not
% Modulo
^ zor / caret / circumflex
& Ampersand
( ) Parenthesis
{ } Curly Braces
[ ] Square Braces
$ Dollar
# Hash
/ Forward Slash
\ Back Slash
* Asterisk
| Bar
_ Underscore
- Hyphen
~ Tilde
` acute, backtick, grave, grave accent, left quote, open quote, or a push
What is a variable?
In C Programming Variable is a storage location in Main memory (RAM) of computer associated by the “C” Compiler
to manipulate different types of data. Variable holds data that can be modified during program execution.
Assigning Name to a variable
• We can use A to Z, a to z, 0 to 9 and underscore (“_” ) to give name to a variable.
• No other special characters should be used.
• The first character of the variable should always a letter or underscore. Never use number as the first
character.
• Variable name in “C” Language is case sensitive. It means “num”, “Num” & “NUM” are three different
variable name.
• No space should be used within the variable name.
Invalid variable name: 2num, 2_sum, 3num_, account no
Valid variable name: Num, sum, num_1 & _av etc.
Keywords / Reserved words
When C Compiler is designed at that time some words are
reserved to perform specific task, those words are called “Reserved
Keywords”. These reserved keywords should not be used as any variable
or function name. If we do so then error occurred.
Data Type in “C”
The kind of data that the variable may hold in a programming language is called Data Type. There is various
types of data that is to be manipulated in C programming such as Integer, Floating Point, Character, String, Real etc.
Integer Data Type (int)
In this kind of data type we store an integer number like 1, 2, 56, 237, 32767 etc.
The keyword used to denote this kind of Data Type is “int”
Data Range: -32768 to 32767
Default value of Integer variable is 0
Declaration of Integer variable
Syntax
Datatype variableName;
Datatype variableName = value;
Datatype variableName1 = value1, variableName2 = value2, variableName3 = value3;
Example
int num1; (Only Variable is declared)
int num2 = 326; (variable is declared & value 326 is assigned to the variable)
int sum = 0, num3 = 124, num4 = 332; (Multiple variable declared and assigned with its value)
Floating Point Data Type
In this kind of data type we store a floating point number like 1.23, 2.56, 56.0001, 237.00 etc.
The keyword used to denote this kind of Data Type is “float”
Data Range: 3.4 x 10
-38
to 3.4 x 10
38
Default value of floating point variable is 0.00000
Declaration of Float variable
Syntax
Datatype variableName;
Datatype variableName = decimalvalue;
Example
float num1; (Only Variable is declared)
float num2 = 326.34; (variable is declared & value 326.34 is assigned to the variable)
float average = 0.00; (variable is declared & value 0.000000 is assigned to the variable)
Character Data Type
In this kind of data type we store a character like a, b, c, D, E, F, 1, 6, $, &, % etc.
The keyword used to denote this kind of Data Type is “char”
Data Range: -128
to 127 (ASCII Codes data)
Default value of character variable is null
Declaration of character variable
Syntax
Datatype variableName;
Datatype variableName = ‘value’;
Example
char Alphabet; (Only Variable is declared)
char First_Alphabet = ‘A’; (variable is declared & value ‘A’ is assigned to the variable)
char Symbol_Dollar = ‘$’; (variable is declared & value ‘$’ is assigned to the variable)
String Data Type
In this kind of data type we store multiple characters like Ram, Unitty2019, Akash Kumar, 25A@ etc.
The keyword used to denote this kind of Data Type is “string”
Data Range: as per the available memory
Default value of string variable is null
Declaration of String variable
Syntax
datatype variableName[no of character to store];
datatype variableName [no of character to store]= {“value”};
Example
char Name[20]; (Only Variable is declared)
char First_Name[15] = {“Akash Kumar”}; (variable is declared & value “Akash Kumar”
is assigned to the variable)
char Last_Name[15] = {“Bandichhor”}; (variable is declared & value “Bandichhor”
is assigned to the variable)
string Fruit[10] = {“Apple”}
Declaration of Different Variables & Assigning its Values
✓ When we create a variable with a name than that is called “declaration of variable”.
✓ When we assign the first value to the variable than that is called “Initialization of the variable”.
✓ If we do not assign any value to a variable then the default value will be “0” in case of integer & float
and “null” in case of char & string variable. But it will not initiate with a value and program may not
work.
Declaring Integer variable
DataType VariableName;
int num1; (a variable is created with a name “num1” with default garbage value 0 or 1)
int num2, num3, num4; ( a group of variables are created named
num2 num3 & num4 with default value 0)
int num5 = 24; (a variable is created with a name “num5” with assigned value 24)
int num6 = 5, num7 = 84; ( a group of variables are created named
num6 with assigned value 5 & num 7 with assigned value 84)
Assigning a variable separately
int num8; (a variable is created with a name “num8” with default value 0)
num8 = 75; (num8 is assigned with a value 75 here)
Declaring Floating Point variable
DataType VariableName;
float num1; (a variable is created with a name “num1” with default value 0.00)
float num2, num3, num4; ( a group of variables are created named
num2 num3 & num4 with default value 0.00)
float num5 = 24.45; (a variable is created with a name “num5” with assigned value 24.45)
float num6 = 5.00, num7 = 84.67; ( a group of variables are created named
num6 with assigned value 5.00 & num 7 with assigned value 84.67)
Assigning a variable separately
float num8; (a variable is created with a name “num8” with default value 0.00)
num8 = 75.34; (num8 is assigned with a value 75.34 here)
Declaring character variable
DataType VariableName;
char chr1; (a variable is created with a name “chr1” with default value ‘null’)
char chr2, chr3, chr4; ( a group of variables are created named
chr2 chr3 & chr4 with default value ‘null’)
char chr5 = ‘y’; (a variable is created with a name “chr5” with assigned value ‘y’)
char chr6 = ‘n’, chr7 = ‘$’; ( a group of variables are created named
chr6 with assigned value ‘n’ & chr7 with assigned value ‘$’)
Assigning a variable separately
char chr8; (a variable is created with a name “chr8” with default value ‘null’)
chr8 = ‘P’; (chr8 is assigned with a value ‘P’ here)
Declaring string variable
DataType VariableName;
string str1; (a variable is created with a name “str1” with default value “null”)
string str2, str3, str4; ( a group of variables are created named
str2 str3 & str4 with default value “null”)
string str5 = “Unitty Academy”; (a variable is created with a name “str5” with
assigned value “Unitty Academy”)
string m_brand1 = “Apple”, m_brand2 = “Samsung”;
( a group of variables are created named m_brand1 with assigned value
“Apple” & m_brand2 with assigned value “Samsung”)
Assigning a variable separately
string country; (a variable is created with a name “country” with default value “null”)
country = “India”; (country is assigned with a value “India” here)
Static Variable in C
A Static variable is initialized only once, when the program is compiled. It is never initialized again. If it is not
initialized by the user then it initializes the value “0” (zero) to the variable. The static variable exists in the memory
until the program termination.
Syntax:
static data_type var_name = var_value;
static int count = 0;
some interesting facts about static variables in C.
1) A static int variable remains in memory while the program is running. A normal or auto variable is destroyed
when a function call and its role is over.
For example below program prints “1 2”
Difference between Normal variable & Static Variable
Normal Variable or Auto variable
Static Variable
1. The normal variable is declared again and again
when a function is run.
2. The normal variable store a garbage value between
“0” and “1” randomly, if we do not initialize it, so
result differs when run in different computer.
3. The value of normal variable ended when the
function is ended.
4. The value of this variable is used only within its
function.
5. It is a local variable.
1. The Static variable Declare only once in a program.
2. The Static variable stores “0”, if we do not initialize
it, so it runs without any error.
3. The value of static variable exists until the program is
ended.
4. The value of static variable is used anywhere in the
program.
5. It is a global variable.
Program Example
#include <stdio.h>
int fun()
{
static int count = 0;
count = count + 1;
return count;
}
int main()
{
printf("%d ", fun());
printf("%d ", fun());
return 0;
}
Output:
1 2
Second example with normal variable
#include<stdio.h>
int fun()
{
int count = 0;
count++;
return count;
}
int main()
{
printf("%d ", fun());
printf("%d ", fun());
return 0;
}
Output
1, 1
How to Choose correct Data type for the program
For selection of data type we need to concern on the following points…
Estimate the output value of the program that it falls under which data range. (see data range table)
a. If the output value may positive then take unsigned data type
b. Any variable that may contain decimal value or the output may the decimal then take that variable as
float data type.
c. If storing value is a single character than take char data type.
d. If storing value is multiple characters than take string data type.
e. If output may null then we can choose a void data type.
Constant /or/ Literal
In a program a name may be assigned to store a data. If that data remains the same throughout the program
execution, then it is called a “constant” or “literal”. A value written as constant for a program never change but if it is
written as variable then it may change.
There are three types of Constants
1. Character Constant
2. String Constant
3. Numeric Constant
Character constant
Character constant is a single character, single digit or a single symbol enclosed with a pair of single
quotation mark ‘ ’ .
Example: ‘A’ ‘c’ ‘2’ ‘#’ etc
String constant
String constant is a sequence of alpha numeric characters enclosed with a pair of double quotation mark “ “
Example: “apple” “Table No 21” “*123#” etc
Numeric constant
Numeric constant has a constant value in numbers. The value may positive or negative number. There are
four types of numeric constant.
a. Integer constant
b. Floating point constant
c. Octal Constant
d. Hex constant
Integer Constant
Integer constant are the whole no with positive or negative value. It may short or long data type.
i.e 5 124 -65 0 -789 or 34456567787 etc
Floating-Point Constant
Floating-Point constant are the fractional number. It has real value with positive or negative value. It may be
written in two forms as fractional or exponential.
Fractional i.e. 5.23 124.43 -65.21 0.26 etc
Exponential i.e. 3.7E12 4.2E-15 etc.
Octal Constant
Octal constant are the integer number with a base of 8. The digit allowed in the system are 0 to 7. It may
positive or negative. It is written as preceding the digit “0”.
Octal No i.e. 005 0124 -098 026 etc
Hex Constant
Hex constant are the Hexa-decimal number with a base of 16. The digit allowed in the system are 0 to 9 and
A to F. It may positive or negative. It is represented as preceding the “0x”.
Hexa-Decimal No i.e. 0x5 0x124 -0x98 0x26 etc
Symbolic Constant
A symbolic constant is represented as a name of a symbol.
Symbolic Constant i.e. pi etc.
Declaring a constant
Syntax
#define constantName constantValue
Example
#define organization “unitty academy” (String Constant)
#define vowel2 ‘e’ (character Constant)
#define num1 24 (integer constant)
#define increment 2400.00 (floating point constant)
#define oct1 035 (octal constant)
#define hexa1 0x54 (Hexa constant)
#define pi 3.14 (Symbolic constant)
Writing comment in a program
Comment in “C” program is a statement which is escaped by the compiler for execution. The “C” compiler
never executes these lines. Comments are of two types.
a. Single line comment (Double forward slash ”//” is used before the comment text )
b. Multi-Line Comments (a forward slash with asterisk “/*” is used before the text & an asterisk with
forward slash “*/” is used after the comment text.
How to write comments in a program
// This is a single line comment
// This line also skipped by compiler.
/* Programmer Name: Abinash Kumar
This program is developed to identify the prime number
Through user entry */
Statement in “C”
Statement is a line of instruction which display the desired text of user or output value of a program. It is
written in a parenthesis with double quotation following the command “printf”.
Syntex: - printf(“Write the text to display”);
Example: - printf(“My Institute Name is Unitty Academy, Sinapali”);
Runtime Library in “C”
A runtime library is a file that contain one or more pre-written programs to perform specific & commonly
used function. It is used in high level languages like “C”, “C++” etc. Each runtime library file contains separate code to
perform separate task by using its predefined functions. These files are also called header file.
Example: -
stdio.h This file contains the Basic input/output functions
conio.h This file contains console input/output functions
math.h This file contains all mathematical functions
geomatry.h This file contains Geometrical functions
graphics.h This file contains functions to perform 2D & 3D graphics
etc…
Functions in “C”
A function is a sub-program that contains instruction or statement to perform a specific computation on its
variable.
Function is defined as the action carries out by a program or subroutine. In “C” Compiler the most important
and useful function is “main()” function. A function in “C” is similar to a subroutine or procedure in other procedural
language like PASCAL. When “C” compiler run a program at first the “main()”function is invoked (called) then other
functions.
Delimiter in “C”
After writing a function name like main(), there are a pair of curly braces to denote the beginning and end of
the function body. That braces are called the delimiter. The Opening curly braces denote the initiation of the
function body & the Closing curly braces denotes the end of the function body.
Structure of a Program in “C”
Library Files
Main function
Delimiter Start
Program Statement 1
Program Statement 2
.
.
.
Delimiter end
(Program End)
Example of a sample “C” Program.
#include<stdio.h>
main()
{
printf(“/n I learn computer training at Unitty Academy, Sinapali”);
printf(“/n The sum of 5 & 6 is %d”, 5+6);
} Argument List (it may a function, variable, value or all)
Control String
Format Specifier in “C”
The printf() function is the most important function in “C” to display the formatted text or output. To format
the output data it needs some format specifiers according to the “Data Type” used for the concern variable.
Format specifier is a single character followed by “%” sign which specify the text or number to display in the
given format.
%c is used to display a single character
%d is used to display a decimal integer
%f is used to display a floating point no
%h is used to display a short integer
%o is used to display an octal no
%s is used to display a string
%x is used to display a hexa-decimal no
Example of a sample program to display different variables declaration with its output value using format specifier.
#include<stdio.h>
main()
{
// This program will display the output according to the format specifiers used
float salary = 20000.00;
int num1 = 4540;
short int num2 = 125;
printf("\n The Salary is Rs %f", salary);
printf("\nThe intiger no is %d ", num1);
printf("\n The short intiger no 2 is %h", num2);
printf("\nThe octal no of 125 is %o", num2);
printf("\nThe hexa-decimal no of 4540 is %x", num1);
printf("\n%f is The Salary", salary);
}
printf("\n The Salary is Rs %f", salary);
in this statement \n is used to create a line break.
Important Note: -
o Where the format specifiers are took place at that position the value of the concern variable will
displayed.
o We can use multiple format specifiers in the control string to use more than 1 variable in the
argument list respectively for correct output. Example
▪ printf("\n The integer no is %d \n The octal no of 125 is %o", num1, num2);
• Output 1 is The integer no is 4540
• Output 2 is The octal no of 125 is 175
Operator in “C”
The operators are the sign, symbol or word, which operate two or more variable or value in a program. We
need operators to perform arithmetic operation like addition, subtraction, multiplication, division and so on.
There are 7 types of operators in “C” Compiler.
1. Arithmetic Operator
2. Relational Operator
3. Logical Operator
4. Assignment Operator
5. Pointer Operator
6. Special Operator
7. Bitwise Operator
Arithmetic Operator in “C”
An arithmetic operator is a symbol which performs arithmetic operation like addition, subtraction,
multiplication, division & Remainder.
Operator
Symbol used
Form of
operation
Operation done
Addition
+ (Plus)
x + y
Add y to x
Subtraction
- (Minus)
x - y
Subtraction y from x
Multiplication
* (Multiplication)
x * y
Multiply x times to y
Division
/ (Division)
x / y
Divide x by y
Remainder
% (Modulo)
x % y
Divide x by y and output the
remainder
Example Arithmetic Operator used in “C” Program
#include<stdio.h>
main()
{
// This program will calculate the drawn salary of an employee
float salary = 5000.00, incentive = 1000, total_sal = 0, penalty = 0, drawn_sal = 0;
int month = 4, ua_leave = 2;
total_sal = (salary * month)+ incentive;
penalty = (salary / 30) * ua_leave;
drawn_sal = total_sal - penalty;
printf("Dear Employee, Your Monthly Salary is Rs %f. Your Incentive amount is Rs %f. Your Total Salary is Rs %f. But
You took un-authorized leave for %d days, So your penalty amount is Rs %f. Now your drawn salary for %d month is
Rs %f",salary,incentive,total_sal,ua_leave,penalty,month,drawn_sal);
}
/* Output will be
Dear Employee, Your Monthly Salary is Rs 5000.000000. Your Incentive amount is Rs 1000.000000. Your Total Salary
is Rs 21000.0 00000. But You took un-authorized leave for 2 days, So your penalty amount is Rs 333.333344. Now
your drawn salary for 4 month is Rs 20666.666016 .
How to use “dev C++” for “C” Program
Download Dev C++ → Right Click on it → Choose Run as administrator →Click Yes → Click Next → Click Next → Click
Finish. (Now Dev C++ is installed in your computer and a shortcut icon will be shown on the desktop)
How to save a program code for “C”
Double Click on the shortcut icon of “Dev C++” → Choose File Menu →New →Source File →type your programming
code → Go to File menu → choose save → Give a name to your program file →then click save as type dropdown
→choose “C Source Files”→ Click “Save”
How to compile & run a program code in “Dev C++”
Go to Execute menu → choose compile →correct the error in the program if it shows →again compile it →if there is
no error now → Click save button →Go to Execute menu →choose run.
Increment & Decrement Operator
The increment operator in “C” Program is represented by “++” sign and the decrement operator is
represented by “- -” sign. Increment operator increases the value of a variable by adding 1. Decrement operator
decreases the value of a variable by subtracting 1.
Example:
X = 5; here the value of x is 5
++x; here the value of x will be 6
Y = 8; here the value of Y is 8
--Y here the value of Y will be 7
Again if we write
--x here the value will be 5
++Y here the value will be 8
Note: We can use the following procedure to add or subtract 1 to a variable.
++a or a = a+1 or a+=1
--b or b=b-1 or a-=1
Pre-Increment & Post-Increment Operator
Pre-Increment operator is represented with a “++” sign before the variable name.
Pre increment operator adds the value 1 to the concern variable and then assign the new value to the next
variable.
Pre Increment operator Example
int sum = 0, x = 12;
Sum = ++x; (Here value of x is added with 1 and new value becomes 13 then that value transferred to
the variable “Sum” and now value of sum will be 13).
Post-Increment operator is represented with a “++” sign after the variable name.
Post- increment operator first assign its existing value to the next variable then add the value 1 to the
concern variable and form new value.
int sum = 0, Y = 23;
Sum2 = Y++; (Here value of Y which is 23 is transferred to the next variable “Sum2” and makes the value
of Sum2 to 23 then increase the value of Y by adding 1 and form a new value of “Y” as 24).
x = 12, Y = 23;
Sum3 = x++ + Y + Y++; 58
Sum4 = --y + Y-- + ++x; 59
Precedence of Arithmetic Operators
If we have various arithmetic operators to calculate various values then which arithmetic operator is used to
evaluate first is called Precedence.
But if we have two operators in the same precedence then they are evaluated Left to Right but in case of
increment or decrement operator they are evaluated right to left.
The Highest precedence is evaluated first.
Relational & Logical Operators
The operator which is used to compare between the value of two variables is called relational. Such
as Less than, Greater Than, Greater than equals, not equals etc.
The operator And (&&) and OR (||) is called Logical Operator.
Relational Operator Table
Operator
Operation (Action)
>
Greater Than
>=
Greater than equal to
<
Less Than
<=
Less Than Equal to
==
Equal to
!=
Not Equal to
Logical Operator Table
These operators output the result either “True” or “False”. True represent “1” or “non zero” & False
represent “0”.
x = 5;
y = 7;
x > y; Output 0
y > x; Output “1” or “non zero”
result1 = x > y; Output 0 will stored in the variable result1
result2 = y > x; Output “1” or “non zero” will stored in the variable result2
Example
#include<stdio.h>
main()
{
// This program is the example of Logical & Relational Operators
Int x= 5, y = 8, z = 0, result1 = 0, result2 = 0, result3 = 0, result4 = 0;
result1 = x<=y;
result2 = x>=y;
Operator
Operation
(Action)
&&
And
It evaluate each and every expression.
||
Or
It evaluates all the expression one after another until it
returns true or end of the expression.
!
Not
It reversed the result (makes true if false and make false
if true)
result3 = x!=y;
result4 = x==y;
printf("is x is greater than y %d",x>y);
printf("\n is x is Less than y %d",x<y);
printf("\n is x Less than equals y %d \n is x greater than equals y %d \n is x not equals y %d \n is x equals y
%d",result1, result2, result3, result4);
}
Output of the Program
is x is greater than y 0
is x is Less than y 1
is x Less than equals y 1
is x greater than equals y 0
is x not equals y 1
is x equals y 0
Precedence of Relational & Logical Operator
Pointer Operator
The Pointer operator are the “address of operator” (&) and the “indirection operator” (*). The
“indirection operator” is used to get the content of a file, memory location or cell. The “&” operator
returns the address of the variable.
Example:
Int salary = 5000; Here an integer variable is declared as “salary”
Int *data_in_salary; Here a pointer variable is declared as “data_in_salary”
data_in_salary = &salary; Here address of the data in the variable salary is
assigned to the pointer variable “data_in_salary”.
Program Example
#include<stdio.h>
main()
{
// This program is the example of Pointer Variable
int salary = 5000;
int *data_in_salary;
data_in_salary = &salary;
printf("\n value of salary is %d",salary);
printf("\n value of data_in_salary is %d",*data_in_salary);
*data_in_salary = 25000;
printf("\n value of salary is %d",salary);
}
Output of the Program
value of salary is 5000
value of data_in_salary is 5000
value of salary is 25000
N.B. “When we change the value of a pointer variable (here *data_in_salary ) then the value of the
addressed variable (here salary ) will be changed.”
Special Operator
The Programming Language “C” Contains many different operators but some operators do not
come under any category, they are called miscellaneous or Special Operator.
Example:
Conditional Operator: - ?:
Coma Operator: - ,
Sizeof operator: - sizeof
Syntex
Variable_Name = Expression_1 ? Expression_2 : Expression_3
Here if the condition of the expression 1 is comes true than the value of expression 2 will be assigned to
the variable else the value of expression 3 will assigned to the variable.
Program Example: 1
#include<stdio.h>
main()
{
// This program is the example of special operator (? :)
int target = 5000, incentive = 1000, sales = 6500, x = 0, y = 0, z = 0;
x = sales > target ? incentive : 0;
y = sales < target ? incentive : 0;
z = sales == target ? incentive : 0;
printf(" \n U Get the amount against incentive Rs %d",x);
printf(" \n U Get the amount against incentive Rs %d",y);
printf(" \n U Get the amount against incentive Rs %d",z);
}
Output of Program
U Get the amount against incentive Rs 1000
U Get the amount against incentive Rs 0
U Get the amount against incentive Rs 0
Program Example: 2
#include<stdio.h>
main()
{
// This program is the example of special operator (? :)
int target = 5000, incentive = 1000, sales = 6500;
char = *msg1, *msg2, *msg3;
msg1 = "Bravo, Well don boy, keep it up, promotion is near by u";
msg2 = "hey boy, u do worse duty, be seriour and sale perfectly";
msg3 = "neutral duty, do some more";
printf(" \n %s",sales > 5000 ? msg1 : msg2);
printf(" \n %s",sales < 5000 ? msg1 : msg2);
printf(" \n %s",sales == 5000 ? msg3 : msg2);
}
Coma Operator (Special Operator Category)
Coma operator (,) is used to build a compound expression by putting several expression inside a set
of parenthesis. The expression is evaluated from “Left to Right” & the last evaluated value is the final
value.
Example:
#include<stdio.h>
#include<conio.h>
main ()
{
// This program is the example of coma Operators
char chr1 = 'z', chr2;
printf (" \n The coma operator expression value is %c", (chr2 = chr1, chr1 = getchar ()));
printf (" \n The Original value of C is %c \n", chr2);
}
Output of the Program
f (User entry done here)
The coma operator expression value is f
The Original value of C is z
Sizeof operator
The “sizeof” operator returns the memory size of a variable.
Syntex
sizeof(variable_Name);
Example
sizeof(str1);
Program Example
#include<stdio.h>
main()
{
// This program will calculate the size of the variable
float salary = 5000.00, total_sal = 0, incentive = 1000, penalty = 0, drawn_sal = 0;
int month = 4, ua_leave = 2;
char grade1 = 'A', grade2 = 'b', alpha [26];
printf(" \n Memory size of float variable salary is %d byte", sizeof(salary));
printf(" \n Memory size of char variable grade1 is %d byte", sizeof(grade1));
printf(" \n Memory size of integer variable month is %d byte", sizeof(month));
printf(" \n Memory size of array variable alpha is %d byte", sizeof(alpha));
}
Output of the Program
Memory size of float variable salary is 4 byte
Memory size of char variable grade1 is 1 byte
Memory size of integer variable month is 4 byte
Memory size of array variable alpha is 26 byte
Bitwise Operator
To operate the operand in machine level, we need bitwise operators. A bit is a smallest possible
unit of data storage and it can have only one of the two possible values “0” or “1”.
The bitwise operator is operated using two shift operations.
a. Left Shift Operation
b. Right Shift Operation
Left Shift Operation
The left shift operation shifts the bits to the left for a specified no of bit operation. The sign used to
represent left shift operation is double less than “<<”.
Syntax
Variable_name << No of bits to shift
Example
int num1 = 7, num2 = 12;
num1 << 1 (The new value will be 15)
num2 << 2 (The new value will be 48)
BIT Range for Left Shift
Operation
128
64
32
16
8
4
2
1
Left Shift 1 of 7
0
0
0
0
0
1
1
1
0
0
0
0
1
1
1
1
Left Shift 2 of 12
Original Bit of 7
After left shift to 1
Original Bit of 12
After left shift to 2
Right Shift Operation
The right shift operation shifts the bits to the right for a specified no of bit operation. The sign used
to represent right shift operation is double greater than “>>”.
Syntax
Variable_name >> No of bits to shift
Example
int num1 = 7, num2 = 12;
num1 >> 1 (The new value will be 3)
num2 >> 2 (The new value will be 3)
Original Bit of 7
After right shift to 1
Original Bit of 12
After right shift to 2
Bitwise Operators & Its Meaning
Bitwise Operator
Meaning
&
Bitwise AND
||
Bitwise Or
^
Bitwise xor
~
1’s Complement
>>
Right Shift
<<
Left Shift
Program Example
0
0
0
0
1
1
0
0
0
0
1
1
0
0
0
0
BIT Range for Right Shift Operation
128
64
32
16
8
4
2
1
Right Shift 1 of 7
0
0
0
0
0
1
1
1
0
0
0
0
0
0
1
1
Right Shift 2 of 12
0
0
0
0
1
1
0
0
0
0
0
0
0
0
1
1
Expression
An expression in programming language “C” is a combination of operators, Numbers & Names that
work together to carry out the result.
Types of Expression
There are four types of expression in “C” Language.
a. Constant Expression Ex. 5+6*34/3.5;
b. Integer Expression Ex. J*K+5-a;
c. Float Expression Ex x/y+3.56;
d. Pointer Expression Ex P; &j; P+j;
Type Conversion
The Programming Language “C” Permits us to mix the different types of variable & constant for
calculation. Sometimes it is required to convert a variable to another type, at that time we need
“typecast”. The compiler performs these calculations without intimating the user is called “implicit
conversion”. The programmer may instruct the compiler to convert one type of variable to another type is
called “Explicit Conversion”.
Example of Explicit Conversion (Type Conversion)
Syntax
(Typecast_Datatype)Variable_Name
(Float)x;
(int)Salary;
Printf(“The Converted value of x from integer to float is %f”, (float)x);
Program Example
#include<stdio.h>
#include<conio.h>
main ()
{
// This program is the example Typecast
int x = 5, y = 7, sum =0;
float a = 5, b = 9;
float sum2 = 0, sum3 = 0;
sum = x + y;
sum2 = y/x;
sum3 = a/b;
printf (" \n The value of X is %d and \n the value of Y is %d", x,y );
printf (" \n The Total of X & Y before Typecast %d", sum );
printf (" \n The Total of X & Y after Typecast to float %f", (float)sum);
printf (" \n The division of X & Y before Typecast %f", sum2);
//The below line is example of implicit conversion
printf (" \n The Division of X & Y after Typecast to integer %d", (int)sum2);
printf (" \n The division of a & b before Typecast %f", sum3);
// implicit conversion ends here (autometic converted by the compiler witout informing the user)
printf (" \n The Division of a & b after Typecast to integer %d", (int)sum3);
}
Output of the Program
The value of X is 5 and
the value of Y is 7
The Total of X & Y before Typecast 12
The Total of X & Y after Typecast to float 12.000000
The division of X & Y before Typecast 1.000000
The Division of X & Y after Typecast to integer 1
The division of a & b before Typecast 0.555556
The Division of a & b after Typecast to integer 0
Input / Output Statement
“C” Program allows us to read data from standard input device like Keyboard & Write data to the
standard output device like Monitor (VDU). For this purpose there is some input & output statement is
used.
There are many library functions available for input & output devices. These functions are
categorized into 3 broad categories.
a. Console I/O Function it Receive input from keyboard & Write output to Monitor.
b. Disk I/O Function it read & write to the storage media like Floppy, Hard disk, SD Card etc
c. Port I/O Function it performs various input & output operation to the different ports
like USB, VGA, HDMI, PS2, LAN, Audio port etc.
Console I/O Functions
Formatted Console I/O Functions
Output Function printf(): This function displays the formatted output to the standard output device.
Syntax
printf(“Message Text Format Specifier”, VariableName);
Example
printf(“The sum of x + y is %d”, sum);
input Function scanf(): This function accept the formatted input from the standard input device
“Key Board”.
Syntax
scanf(“Message Text Format Specifier”, addressofVariableName);
Example
scanf(“Enter the value for x and y %d”, &x, &y);
Program Example
#include<stdio.h>
main()
{
// This program will calculate the drawn salary of an employee with user input
float salary = 5000.00, total_sal = 0, incentive = 1000, penalty = 0, drawn_sal = 0;
int month = 0, ua_leave = 0;
printf("Enter no of month ");
scanf("%d", &month);
printf("\n Enter Un Authorised Leave ");
scanf("%d",&ua_leave);
total_sal = (salary * month)+ incentive;
penalty = (salary / 30) * ua_leave;
drawn_sal = total_sal - penalty;
printf("\n You are receving your %d month of sal with %d days of UA_Leave is Rs %f",month, ua_leave,
total_sal);
}
Output of the Program
Enter no of month 5
Enter Un Authorised Leave 7
You are receving your 5 month of sal with 7 days of UA_Leave is Rs 26000.000000
Unformatted console I/O Function
Character Input: - for Character input as unformatted function we use getch(), getche() & getchar()
function.
The getch() & getche() function is very similar as they respond without pressing of enter key of keyboard.
The only different is that the getche() function makes the user entry text visible but the getch() function
donot show the text entered by the user. If we use these two function in any program than we neet to
include the header file “conio.h” in the beginning of the program.
The getchar() reads one character from the key board after the new line character (enter key) is received.
Syntax
char x, y, z;
getch(variableName);
getche(variableName);
getchar(variableName);
Example
getch(x); reads a single character and store it to the variable x without visible user input.
getche(y); reads a single character and store it to the variable y with visible user input.
getchar(z); reads a single character and store it to the variable z after pressing enter key.
Character Output: -
putc()
putchar()
if we have to print a single character in a program the instead of using the formatted output function
printf(), we must use the unformatted putc() or putchar(). For doing this we must enclose the character in
a single quotes (‘ ’).
Unformatted String input & Output: - gets() & puts()
gets() stands for “get the string”. It reads the string entered by the user till the newline character (enter
key press). It can assign the string to an array variable. We must use double quotes (“”) to enclose the
string.
puts() stands for “put the string”. It print the existing string of the variable or text encoded with double
quotes.
Syntax & Example
char name[25];
gets(variablename);
gets(name);
puts(variablename);
puts(name[]);
Program Example of all unformatted functions
#include <stdio.h> //This program is an example ofunformatted character function
#include <conio.h>
main()
{
char c, d, e;
printf("\nEnter a character getchar : ");
c = getchar();
printf("\nEntered character : getchar %c \n", c);
putchar(c);
printf("\nEnter a character 2 getch : ");
d = getch();
printf("\nEntered character getch: %c \n", d);
putch(d);
printf("\nEnter a character 2 getche : ");
e = getche();
printf("\nEntered character getche: %c \n", e);
putch(e);
return 0;
}
Program Output
gets & puts program example
#include <stdio.h> //This program is an example ofunformatted string function
#include <conio.h>
main()
{
char str1[20];
printf("\nEnter Your Name : ");
gets(str1);
printf("\n Your Name is %s \n", str1);
puts(str1);
return 0;
}
Program Output
Your Name is Ramanuj
Ramanuj
Field width Specifier
The printf() function allow the programmer to add formatting to the printed output. A digit preceding the
decimal point in the field width specifier controls the number as it is printed.
When we use field width specifier in the format specifier inside the control string, it set the “zero” before
the integer or after the decimal accordingly.
Example of field width specifier
#include<stdio.h>
main ()
{
// This program is the example field width specifier
int num1 = 3476;
float num2 = 2657.345650;
printf("\n The float no without field width specifier is %f", num2);
printf("\n The float no with field width specifier is %2.3f", num2);
printf("\n The float no with field width specifier is %0.012f", num2);
printf("\n The integer no without field width specifier is %d", num1);
printf("\n The integer no with field width specifier is %8d", num1);
printf("\n The integer no with field width specifier is %08d", num1);
}
Program Output
The float no without field width specifier is 2657.345703
The float no with field width specifier is 2657.346
The float no with field width specifier is 2657.345703125000
The integer no without field width specifier is 3476
The integer no with field width specifier is _ _ _ _3476 (underscore means blank )
The integer no with field width specifier is 00003476
Escape sequence
An escape sequence provides special formatting control on output of the program. It allows us to use Tab,
Line break (new line), Backspace, alert and so on in a program for output. It is also called Execution
character. It is used inside the control string encoded with double quotes. The back slash symbol “\” is
called escape in “C Program”.
Escape Sequence
Escape Sequence
Purpose
\n
It insert a new line
\b
It set a back space
\f
For form feed
\’
It insert single quotes
\\
It insert back slash
\t
It insert a Tab
\r
It return carriage
\a
It Sound an alert
\”
It insert double quotes
Example of escape sequence
syntax
printf(“escape sequence name Your control message of output format specifier”, variablename);
Example
printf(“\n the value of the variable x is %d”, x);
printf(“\n the value of the variable x is \t %d”, x);
Difference between printf() & scanf()
The major difference between scanf() & printf() is that in scanf() the data item argument must be preceded
by the address operator “&”. Example scanf(“%d”,&num1). It direct the system to read integer input from
the user terminal. But in printf() function variable name is written without address operator and it return
the output for the user.
Conditional Statements & Loops
Statements in C are executed one after another is called the normal statement. But a statement
which instructs a system to perform same basic operation again and again until a condition is fulfilled is
called loop. It is the automated power of C Program. These are happens using control statements.
Control statements allow us to change the sequence of instructions for execution. It is of two types…
• Conditional Branching
• Looping
Conditional Branching
When a program decide whether the next statement is to be executed or not based on the result
value of the current expression, is called condition branching.
Looping
When a program performs a set of operation repeatedly until a given condition is fulfilled is called
loop. In loop all the statements inside the loop are executed repeatedly. It is also called “iteration”.
Decision Making
Decision making is a process to execute a specific task according to the conditional requirement.
Ex: - “a friend said to his friend that if it feels too hot then you put the fan switch on”.
If Statement
The “if statement” is a control statement which test a particular condition. Whenever the evaluated
condition comes true the an action is carried out otherwise the given set of instruction is ignored.
Syntax: If (conditional expression)
{Statements};
Example: if (sales>=50000)
{incentive = (sales*10)/100}
Here if a salesman sale a product more than or equal to 50000 then he can gain an incentive upto 10
percent, but if sales below 50000 then no incentive is given to him.
Program Example:
#include<stdio.h>
main()
{
// This program will calculate the incentive of a salesman (if condition)
float sales = 0, incentive = 0;
printf("Enter the sales amount");
scanf("%f", &sales);
if (sales>=50000)
{
incentive = (sales*10)/100;
printf("The incentive amount is %f", incentive);
}
printf("\n note: Please enter the sales amount above 50000");
}
If else Statement
The else part of the “if statement” is run when the “conditional expression” of if statement comes
false. We can call it the false statement.
Syntax
If (conditional Expression)
{True Statement}
else
{false Statement}
Example:
#include<stdio.h>
main()
{
// This program will calculate the incentive of a salesman (if else statement)
float sales = 0, incentive = 0;
printf("Enter the sales amount");
scanf("%f", &sales);
if (sales>=50000)
{
incentive = (sales*10)/100;
printf("The incentive amount is %f", incentive);
}
else
{
incentive = 0;
printf("The incentive amount is %f", incentive);
}
}
Multiple If Statement
In the multiple if statement those statements will run which conditions are fulfilled.
Program Example
#include<stdio.h>
main()
{
// This program will calculate the incentive of a salesman (if else statement)
float sales = 0, incentive = 0;
printf("Enter the sales amount");
scanf("%f", &sales);
if (sales>=50000)
{
incentive = (sales*10)/100;
printf("\n The incentive amount is %f", incentive);
}
if (sales == 0)
{
printf("\n You are fired");
}
if (sales < 50000)
{
incentive = 0;
printf("\n You can avail salary only but The incentive amount is %f", incentive);
}
If else if Statement (Nested if)
In this statement, we can use more than one condition in a program and the program will run only
that single statement of the condition which is fulfilled.
Program Example
#include<stdio.h>
main()
{
// This program will calculate the incentive of a salesman ( if else if statement)
float sales = 0, incentive = 0;
printf("Enter the sales amount\t");
scanf("%f", &sales);
if (sales>=50000)
{
incentive = (sales*10)/100;
printf("\n The incentive amount is %0.2f \t", incentive);
}
else if (sales == 0)
{
printf("\n You are fired");
}
else if (sales < 50000)
{
incentive = 0;
printf("\n You can avail salary only but The incentive amount is %d", (int)incentive);
}
}
The Switch Case Statement
Instead of using if-else-if Ladder, the switch case statement is used. The only different is that in
switch case statement u must have to use the integer constant as the conditional expression but in if-else-
if ladder you can use any datatype variable or constant for conditional expression to return the expected
result.
Syntax
Switch(variablename)
Case integervariablevalue:
Statements;
break;
Break statement is used to block the unwanted statement output after program execution. Because switch
case statement always run all those lines from where the condition comes true. To stop the execution after
the “true” statement, we must use “break” statement.
Not to do in switch case statement.
a. Never use char or string variable for “switch parameter”.
b. Never use decimal constant.
c. Never use character constant.
d. Never use a string for “case level”.
e. Never use variable for “case level”.
Program Example
#include<stdio.h>
main()
{
// This program will calculate the week day name according to day no entry. (Switch case)
int dayno = 0;
printf("Enter the Day no (1 to 7)\t");
scanf("%d", &dayno);
switch(dayno)
{
case 1:
printf("\n Sunday \t");
break;
case 2:
printf("\n Monday \t");
break;
case 3:
printf("\n Tuesday \t");
break;
case 4:
printf("\n Wednessday \t");
break;
case 5:
printf("\n Thursday \t");
break;
case 6:
printf("\n Friday \t");
break;
case 7:
printf("\n Saturday \t");
break;
default:
printf("\n Please enter 1 to 7 \t");
}
}
The Loop construct
The loop or iteration construct directs a program to perform a set of operation again and again until a
specific condition is achieved. This condition cause the termination of the loop. In “C Program” there are
three statements for looping they are
a. while loop
b. do …… while loop
c. for loop
While Loop
The “while loop” allows evaluates a test expression before allowing entry into the loop. It means it is
an “entry control loop”. while loop construct first check the condition and if the condition is come true
then it execute the statements following the loop. Else it ignore the statement and break the looping.
Syntax
while (condition)
{
Statement1
Statement2
………………..
}
Program Example (while loop)
#include<stdio.h>
main()
{
// This program will display the even no from 1 to 100 (while loop statement)
int num1 = 0;
while(num1<100)
{
num1 = num1+2;
printf("\n The Serial No is %d", num1);
}
}
Print the Fibonacci series using while loop
1, 1, 2, 3, 5, 8, 13….. upto 100
Do…. while Loop
The “do …. while loop” is an exit control loop. This loop execute the statement at least once before
checking the test expression (parameter). After execution of the statement it will check whether the test
expression is true or false. If test expression comes true, then it will repeat the statement else it will break
the loop. We must put a semi-colon (;) mark after while statement in do…while loop construct.
Syntax
do
{
Statement 1
Statement 2
Statement ….
}
While (Test Expression);
Program Example
#include<stdio.h>
main()
{
// This program will display the even no from 1 to 100 (do... while loop statement)
int num1 = 0;
do
{
num1 = num1+2;
printf("\n The Serial No is %d", num1);
}
while(num1<100);
}
For…. Loop
It is an entry control loop. The execution process is same like while loop. The only different is that in
for loop we write initial expression, test expression and increment or decrement statement under for loop
parenthesis. So the “For loop” run the initial expression first and once, then run the statement under for
loop then test the expression then increase or decrease the value of the incrementer or decrementor then
it repeat the statements again if the test condition comes true.
Syntax
For (Initial Expression; Test Expression; Incrementor or Decrementor )
{
Statement 1
Statement 2
Statement…
}
Program Example
#include<stdio.h>
main()
{
// This program will display the even no from 1 to 100 (for...... loop statement)
int num1;
for(num1 = 0; num1<100; num1 = num1 + 2)
{
printf("\n The Serial No is %d", num1);
}
return 0;
}
