What is loop in c programming language

some time we need a statement to repeat again and again. In general, statements are executed sequentially. The first statement in a function is executed first and second statement is executes after 1st and and so on.
Programming languages provide various structures that allow for more complicated execution paths.
C programming provides the following types of loops.
There are following types of loops in c

  1. For Loop
  2. while loop
  3. do…while loop

1. For Loop

What is a for loop?

for loop enables a particular set of conditions to be executed repeatedly until a condition is true. In the situation where you would have to print numbers from 1 to 100. What would we do? Will we type in the printf command a hundred times  ? This simple task would take an eternity. By Using a ‘for loop’ we can perform this action only in 3 statements. This is the most basic example of the for loop.
Flowchart of for loop 

How for loop works?

The initialization statement is executed only once.
Then, the test expression is evaluated. If the test expression is false (0), for loop is terminated. But if the test expression is true (nonzero), codes inside the body of for loop is executed and the update expression is updated.This process repeats until the test expression is false.
The for loop is commonly used when the number of iterations is known.
To learn more on test expression (when test expression is evaluated to nonzero (true) and 0 (false)), check out relational and logical operators.
2.while loop

While loop is  similar as  for loop, but have less functionality. A while loop continues executing the statements as the condition in the while remains true.the example is as follows.

syntax of while loop

The syntax of while loop is as follows.


Flowchart of while loop.
How while loop works.
in the following above flowchart  when the condition is tested and the result is false. The loop body will be skipped and the first statement after the while loop will be executed.if the condition is true then the loop is executed again and again
3.do while loop
The do while loop is similar to the while loop but  the body of do while loop is executed once. before  testing  expression.  the do while loop is executed at least once first.
syntax of do while loop 
The syntax of do while loop is as follows.

while(condition true);

Flowchart of do while loop

How do while loop works
In do while loop the first  statement  is tested if the condition is true then the program is executed otherwise the program is skip and  if the condition is true the program is executed again and again until the condition is false.