Looping In C Language

Introduction To Looping In C Language
*A loop statement allows us to execute a statement or group of statements
multiple times.
*By The Help Of Looping statements are executed sequentially.
Types of Looping Statements In C Language::
1)while Loop
2)for Loop 
3)do..while Loop
4)nested Loop
Let Us Know About These Statements With The Help Of Suitable Example:
while Loop:-
*This Loop tests the condition before executing the loop body.
*It Repeats a statement or group of statements while a given condition is true.
*Loop Is Terminated When Condition Becomes False
Geral Syntax:-
while(given_condition)
{
----- Statement 1;

 ----- Statement 2;
----- Statement 3;
}
Let's Understand This By Example:
#include <stdio.h>
int main ()
{
/* local variable definition */
int i = 19;
/* while loop execution */
while( i < 100 )
{
printf("value of i= %d\n", i);
i=i+19;
}
return 0;
}
Explanation:
This Loop Is execute until i=95(i<100) after that
it return to main body, and The Output Is Given In Picture:
for Loop:
*It allows you to efficiently write a loop
that needs to execute a specific number of times.
Syntax (for loop)
 for ( initialization; condition; increment/decrement )
{
statement(s);
}
*initialization means we have to assign initial value to variable
*condition means The expression which have to do.
*Increment/decrement allows you to update any loop control variables
*The condition is now evaluated again. If it is true, the loop executes and
the process repeats itself (body of loop, then increment step, and then
again condition). After the condition becomes false, the ‘for’ loop
terminates.
Example Program:-
#include <stdio.h>
int main ()
{int x;
/* for loop execution */
for(x=1; x< 25; x = x + 5 )
{
printf("value of x= %d\n", x);
}
return 0;
}
do..while Loop:-
*It is more like a while statement, except that it tests
the condition at the end of the loop body.
*It Means That the statement(s) in the loop executes
once before the condition is tested.
Syntax (do..while loop)
do
{
statement(s);
}
while(Required_condition );
*If the condition is true, the flow of control jumps back up to do, and the
statement(s) in the loop executes again. This process repeats until the given
condition becomes false.
Example Program:-
#include <stdio.h>
int main ()
{
/* local variable definition */
int x = 50;
/* do loop execution */
do
{
printf("value of x= %d\n", x);
x = x*2;
}while( x < 500 );
return 0;
}
In This Program Condition is Chacked After Once Executation
Output Is Given In Picture>>.
Nested Loops:
When We use one loop inside another loop this is called nesting of
loops.In C Programming It Is Allowed.
Syntax:(nested loops):-
1)for loop nesting syntax:
for ( initialization; condition; increment/decrement )
{
for ( initialization; condition; increment/decrement )
{
statement(s);//outer loop statement
}
statement(s);//inner loop statement
}
2)nested while loop syntax:-
while(condition1)
{
while(condition2)
{
while(condition)
{
statements;
}
statements;
}
3)Nested do.while loop Syntax:-
do
{
statement(s);
do
{
statement(s);
}
while( condition 1);
}
while( condition 2);
Example Program:
Given Program Prints Prime No Between
2 to 50.
#include <stdio.h>
int main ()
{
/* local variable definition */
int x, y;
for(x=2; x<50; x++) {
for(y=2; y <= (x/y); y++)
if(!(x%y)) break;
// if factor found, not prime
if(y > (x/y))
printf("%d is prime\n", x);
}
return 0;
}
The Output Of This Program Is all
Prime No Between 2 to 50.This Is
Shown In Output Screen Picture.