Loop Control Structures in C
Sometimes we may come across a case where we need to perform a task multiple times. In that case we may repeat code several times or write that code inside a loop.
Consider you have to repeat a code for hundred times, so it is feasible to write it in loop rather than repeating the code.
In C there are three looping methods for, while, do-while which can be used to loop certain part of our program.
[1] for loop
for loop consists of three parts – Initialization, Test Condition and Increment or decrement statement.
Initialization occurs only once, at the start of loop.
Test condition is checked for every iteration, if it is true then the statement or block of statements will be executed.
Increment or decrement is done after the execution of the block of statement. It is important as it will take us to the final condition and terminate the loop.
Syntax
| //for single statement for ( initialization; test condition; increment/decrement ) statement;//for multiple statement for ( initialization; test condition; increment/decrement ) |
//C code to illustrate do-while loop
#include <stdio.h>
int main()
{
int a = 10;
do
{
printf("value of a: %d\n", a);
a--;
} while (a > 0);
return 0;
}
| $ gcc for.c $ ./a.out Number from 1 to 10: 1 2 3 4 5 6 7 8 9 10$ |
[2] while loop
The statements within the while loop will keep on executing until the condition remains true.
Syntax
| initialize loop counter; while (test loopcounter using a condition) { //statements to execute in loop increment/decrement loopcounter; } |
#include <stdio.h>
int main()
{
int a = 10;
while (a > 0)
{
printf("value of a: %d\n", a);
a--;
}
return 0;
}
| $ gcc while.c $ ./a.out 10 9 8 7 6 5 4 3 2 1 $ |
[3] do-while loop
The while and for loop tests the condition at the top. But do-while test the condition after the body is executed once. If the test condition is true it will keep on executing.
Syntax
| do { statements; }while (expression); |
//C code to illustrate do-while loop
#include <stdio.h>
int main()
{
int a = 10;
do
{
printf("value of a: %d\n", a);
a--;
} while (a > 0);
return 0;
}
| $ gcc do.c $ ./a.out 10 9 8 7 6 5 4 3 2 1 $ |
If you like the post Loop Control Structures in C, please share the feedback!
also see
| C Programming language |
Go Programming language |
| Linked List | Array |
| Simplification | Queue |
| DBMS | Reasoning |
| Aptitude | HTML |
