How Loops (for,while,do..while) Works in C Language

In This Post you will learn how loops work in c language with the help of examples. Before learning how loops work in c language?. We should know why we use loops?

For example if we want to print ten times hello launchpadlwd then we have to write print ten times, but writing printf ten times is not a good technique, instead we can use loops and perform same task in a single line let’s see how?

Example 1 using printf:      

#include<stdio.h> int main() {    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    printf("hello launchpadlwd");    return 0;   }

       

Example 2 using loop:

#include<stdio.h> int main() {    int i;    for(i=1;i<=10;i++)    printf("welcome to launchpadlwd");    return 0;   }

So we, can see the output of example 1 and 2 are same but there is difference in code by using loops we can perform the same program in less code.

C Programming has three types of loops:

•          For loop

•          While loop

•          Do...while loop

 For loop in c language

Syntax of for loop is :

    Rotate your phone to see the table:

1                               2                       4     For(initializationstatement;testexpression;updatestatement) {                         3    // statements inside the body of for loop }

           

How for loop works?

1.The initialization statement is executed first and only once.

 2.Then, the test expression is evaluated at second. If the test expression is evaluated to false, the for  loop is terminated(exit).

 3.However, if the test expression is evaluated to true, statements inside the body of for loop are executed, and the update expression is updated.

 4.Again the test expression is evaluated.

 5.This process goes on until the test expression is false. When the test expression is false, the loop terminates.

Example 3 for loop in c     

#include<stdio.h> int main() {    int i;    for(i=1;i<=5;i++)    printf(“%d",i);    return 0;   }

·        Step 1 i is initialized to 1.

 

·        Step 2 The test expression i < 5 is evaluated. Since 1 less than 5 that is true, then the body of for loop is executed.

 

·        Step 3 This will print the 1 (value of i) on the screen.

 

·        Step 4 The update statement i++ is executed. Now, the value of i will be 2. Again, the test expression is evaluated if found true, then body of for loop is executed else the loop is terminated. This will print 2 (value of i) on the screen.

 

·        Again, the update statement i++ is executed and the test expression i < 5 is evaluated. This process goes on until i becomes 5.

 

·        When i becomes 5, i < 5 will be false, and the for loop terminates. 

While loop 

While studying for loop we known that the number of times loop will execute, i.e. the number of times the loop body will be executed is known to us. while loops are used in situations where we do not know the exact number of times the loop will execute. The loop execution is terminated on the basis of test condition

Syntax of while loop is:  

Rotate your phone to see table:

While(Text Expression) {      // Statements inside the body of while loop }

How while loop works?

Step 1 The while loop evaluates the test expression inside the parenthesis ().

Step 2 If the test expression is true, statements inside the body of while loop are executed. Then, the test expression is evaluated again.

Step 3 The process goes on until the test expression is evaluated to false.

Step 4 If the test expression is false, the loop terminates (ends).

#include <stdio.h> int main() {     int a = 1;         while (a <= 5)     {         printf("%d\n", i);         i++;     }       return 0; }

Do...While loop 

Do...While loop

The do..while loop is similar to the while loop with one important difference In do while loop the loop execution is terminated on the basis of test condition. The main difference between do while loop and while loop is do while loop condition is tested at the end of loop body, i.e do while loop is exit controlled whereas the other two loops are entry controlled loops.

Note: In do while loop the loop body will execute at least once irrespective of test condition.

Do..while loop syntax:

Rotate your phone to see the box:

Do {   //statements inside the body of do..while loop } While(Text Expression);

How do...while loop works?

Step 1 The body of do...while loop is executed once. Only then, the test expression is evaluated.

Step 2 If the test expression is true, the body of the loop is executed again and the test expression is evaluated.

Step 3 This process goes on until the test expression becomes false.

Step 4 If the test expression is false, the loop ends.

Example of Do..while loop:

#include <stdio.h> int main() {     Int a=1;       // the body of the loop is executed at least once     do     {         printf("%d”, a);         i++;     }     while(number i<=5);       return 0; }

 

To Study About C Language Please Visit This Link:

https://www.launchpadlwd.xyz/search/label/C%20LANGUAGE?&max-results=8