C language loops | for loop

For Loop      While Loop      Do while Loop

Loops help us to execute specific number of statements a specified number of times. “C” language provides 2 types of loops.

(i). Entry control loops (for loop and while loop)

(ii). Exit control loops (do while loop)

These statements are also known as iteration or looping statements.

Entry control loops

Entry control loops are the loops in which the condition is checked first and then the control enters the loop.
In “C” language we have two entry control loops.

(i) for loop
(ii) while loop

For loop

for loop is an entry control loop. In for loop we are required to pass three arguments.

Syntax:
(i).
for(A;B;C)
single Statement;
(ii).
for(A;B;C)
{
Statements;
Statements;
Statements;
}
A : initialization
B : Test condition
C : Increment / decrement

Syntax:

for(initialization ;test condition ;increment/decrement)
{
Statements;
Statements;
Statements;
}

Note: all the arguments passed in for loops are optional.
For loop can take following forms

1. for(a;b;c)
2. for(;b;c)
3. for(a;;c)
4. for(a;b;)
5. for(a;;)
6. for(;b;)
7. for(;;c)
8. for(;;)

For loop examples:

Example:1
C program to print numbers from 1 to 10
Sol:

#include <stdio.h>
 int main()
 {
     int i;
     for(i=1;i<=10;i++)
     {
         printf("%d\n",i);
     }
 return 0;
 }

Output:

1
2
3
4
5
6
7
8
9
10

Example:2
Write a C program to print numbers from 1 to 10 in reverse order
Sol:

#include<stdio.h>
 int main()
 {
     int i;
     for(i=10;i>=1;i--)
     {
         printf("%d\n",i);
     }
 return 0;
 }

Output:

10
9
8
7
6
5
4
3
2
1

Example:3
Write a C program to print all even numbers from upto 20
Sol:

#include <stdio.h>
 int main()
 {
     int i;
     for(i=2;i<=20;i=i+2)
     {
         printf("%d\n",i);
     }
 return 0;
 }

Output:

2
4
6
8
10
12
14
16
18
20

Example:4
Write a C program to print all even numbers from upto 20 in reverse order
Sol:

#include <stdio.h>
 int main()
 {
     int i;
     for(i=20;i>=2;i=i-2)
     {
         printf("%d\n",i);
     }
 return 0;
 }

Output:

20
18
16
14
12
10
8
6
4
2

Example:5
Write a C program to print all odd numbers from upto 25
Sol:

#include <stdio.h>
 int main()
 {
     int i;
     for(i=1;i<=25;i=i+2)
     {
         printf("%d\n",i);
     }
 return 0;
 }

Output:

25
23
21
19
17
15
13
11
9
7
5
3
1

C Language Programming Tutorial

C Language Tutorial Home     Introduction to C Language     Tokens     If Condition      goto statement and Labelname     Switch Statements     For loop     While Loop     Do while loop     break and continue     Functions     Recursion     Inbuild Functions     Storage Classes     Preprocessor     Arrays     Pointers     Structures and Unions     File Handling     Projects

Number Of Visitors

0238239