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In C, and all other modern programming languages, iteration statements (also called loops) allow a set of instructions to be repeatedly executed until a certain condition is reached. This condition may be predetermined (as in the for loop) or open-ended (as in the while and do-while loops).

In another way we can say, A loop can be used to tell a program to execute statements repeatedly. Or we can say that a loop repeatedly executes the same set of instructions until a termination condition is met.

Why Loop is Important ?

Suppose that you need to display a string (e.g., Welcome to atnyla! ) a hundred times. It would be tedious to have to write the following statement a hundred times:

printf("Welcome to atnyla!");
printf("Welcome to atnyla!");
...
...
...
printf("Welcome to atnyla!");
 

So, how do you solve this problem? C hava a powerful feature called a loop that controls how many times an operation or a sequence of operations is performed in succession. Using a loop control statement, you simply tell the computer to display a string a hundred times without having to code the print statement a hundred times, as follows:

Program

 #include
void main(){
	
int count = 0;
   while (count < 100) {
   printf("Welcome to atnyla! \n");
   count++;
   }
   
}

Output

 Welcome to atnyla!
Welcome to atnyla!
....
....
....
Welcome to atnyla!
Welcome to atnyla!
100 times
Press any key to continue . . .

Explanation

The variable count is initially 0 . The loop checks whether count < 100 is true . If so, it executes the loop body to display the message Welcome to atnyla!and increments count by 1 . It repeatedly executes the loop body until count < 100 becomes false. When count < 100 is false (i.e., when count reaches 100 ), the loop terminates and the next statement after the loop statement is executed

Another important Example ?

Program

#include
void main(){
 int n = 10;
  while(n > 0) {
  printf("%d \n",n);
  n--;
  }
   
}

Output

10
9
8
7
6
5
4
3
2
1
Press any key to continue . . .

Types of Loop

Java provides mainly three types of loop statements:whileloops, do - whileloops, andforloops.

Sr.No.	Loop & Description
1	while loop Inwhile loopfirst checks the condition if the condition is true then control goes inside the loop body otherwise goes outside of the body.
2	do...while loop A do while loop is a control flow statement that executes a block of code at least once, and then repeatedly executes the block, or not, depending on a given condition at the end of the block (in while).
3	for loop For Loop is used to execute set of statementsrepeatedlyuntil the condition is true.

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