Looping in C#

Looping in C#

Looping in programming language is a way to execute a statement or a set of statements repeatedly for a number of times depending on the result of condition to be evaluated. The result of the  condition should be true for the statements within the loop body to be executed statements.

Loop Category

There are mainly two categories of Loop; these are

Entry Controlled Loops

These types of loop have their conditions tested in the beginning of the loop body. example are While loop and for loops.

Exit Controlled Loops

These are loops in which conditions are tested at the end of loop body. do-while is an example of exit controlled loop.
Note: In Exit Controlled Loops, loop body will be evaluated for at-least one time as the testing condition is present at the end of loop body.

Example of entry controlled loops

while loop


In while loop, the test condition is given in beginning of loop and all statements are executed till the given boolean condition is satisfied, when the condition becomes false, the control will be out from the while loop.

Syntax:

while (bool condition)
{
    loop statements
}

code snippets
using system;
class WhileExample
{
   public static void main()
   {
       var w =1;
        while ( w <=4)
        {
            Console.WriteLine("Printing this 4 times");
            w++;
        }
    }
}

for loop

This kind of loop executes the statements within the body of the loop until a specified condition returned false.

syntax:
for(initialization;condition;steps)
{
   statements to be executed
}
from the above syntax, we can see that the for loop construct has three main parts such as variable initialization, loop condition and the steps.

variable initialization: This part involves the declaration of variable to be used for loop counter
condition: boolean expression that returns true or false.
steps: This is involves the increment and decrements  


code snippets
for(var i=0;i<=10;i++)
{
   Console.WriteLine("The value of i is :{0}", i.ToString());
}

Infinite for loop

for(;;)
{
    Console.WriteLine(2);
}

Example of exit controlled loops

Exit controlled loop is a Loop where test condition is checked after executing the loop body.

In the exit controlled loop, the body of the loop runs at least once.

do ... while is an example of exit controlled loop

Syntax

do

{

     //Loop body

}while(expression);

example of do...while loop

int i=10;

do

{

   Console.WriteLine("i is " + i.ToString());

}

while(i <5);

The main differences between entry controlled and exit controlled loops

1.  In entry controlled loop, test condition is checked first before the loop body executes while exit controlled loop runs the loop body at least once before the test condition is checked.

2.  if test condition failed, the loop body will not be executed in entry controlled loop while the loop body will run at least once in case of exit controlled loop

3.  for loop and while loop are examples of entry controlled loop while do...while is an example of exit controlled loop

4.  entry controlled loop is used when checking the test condition before the loop body runs is mandatory while we use exit controlled loop when we want to execute the loop body at least once