C do-while

do-while is similar to a while loop and used when a set of statements have to be repeatedly executed at least once untile a certain condition is reached. When we do not know exactly how many time a set of statement have to be repeated do while can be used.

How do-while Works

• Step 1:-
  The initialization statement is executed first
• Step 2:-
  Then, the test expression is evaluated. If the test expression is evaluated to false, then the while loop gets terminated and the control comes out of the while loop.
• Step 3:-
  if the test expression is evaluated to true,The statements defined inside the while loop will repeatedly execute until the given condition fails.
• Step 4:-
  After successful execution of statements inside the body of the while loop, the update expression is executed.
• Step 5:-
  Again the test expression is evaluated.

Example with dry Run Concepts

 #include<stdio.h>
 #include<conio.h>
 void main()
 { 
 int i=1; 
 do
 {
 printf(“%d\n”,i); 
 i++; 
 }while(i<=5);
 getch();
 }

Above Program Explanation

• Step 1:-
  We declared integer variables called i. The initialization statement is executed. i.e i=1
• Step 2:-
  Next, print i value Then, the test expression is evaluated. i.e i is less than or equals to 5 or not (i <=5 ) hear condition is true so statements inside the body of the while loop are executed, and it will print the value of i i.e 1
• Step 4:-
  After successful execution of statements inside the body of the do, the update expression (i.e i++) means it incremented by 1 now the value of i is 2
• Step 5:-
  Again the test expression is evaluated. and repeat step 2 till the condition is false
• Step 5:-
  when the condition is false means the value of i will be 6 then while loop gets terminated and the control comes out of the loop.

Difference between while loop and do-while loop.

C for loop MCQ Question

int main()
{
    int a=65;
    
    do
    {
        printf("%d ", a);
        a++;
    }while(a <= 65);

    return 0;
}

1. 65
2. 87
3. 78
4. error

int main()
{
    int a=65;
    
    do
    {
        printf("%d ", a);
        a++;
        if(a > 68)
            break;
    }while(1);

    return 0;
}

1. 65 66 67 68
2. 65 66 67
3. 65 66 67 68 69
4. error