do-while Loop

do while loop in C

The do while loop is a post tested loop. Using the do-while loop, we can repeat the execution of several parts of the statements. The do-while loop is mainly used in the case where we need to execute the loop at least once. The do-while loop is mostly used in menu-driven programs where the termination condition depends upon the end user.

do while loop syntax

The syntax of the C language do-while loop is given below:

1. do{  
2. //code to be executed  
3. }while(condition);  

Example 1

1. #include<stdio.h>  
2. #include<stdlib.h>  
3. void main ()  
4. {  
5.     char c;  
6.     int choice,dummy;    
7.     do{  
8.     printf("\n1. Print Hello\n2. Print Javatpoint\n3. Exit\n");  
9.     scanf("%d",&choice);  
10.     switch(choice)  
11.     {  
12.         case 1 :   
13.         printf("Hello");   
14.         break;  
15.         case 2:    
16.         printf("Javatpoint");  
17.         break;  
18.         case 3:  
19.         exit(0);   
20.         break;  
21.         default:   
22.         printf("please enter valid choice");      
23.     }  
24.     printf("do you want to enter more?");   
25.     scanf("%d",&dummy);  
26.     scanf("%c",&c);  
27.     }while(c=='y');  
28. }  

Output

1. Print Hello
2. Print Javatpoint
3. Exit
1
Hello
do you want to enter more?
y

1. Print Hello
2. Print Javatpoint
3. Exit
2
Javatpoint
do you want to enter more?
n

Flowchart of do while loop

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do while example

There is given the simple program of c language do while loop where we are printing the table of 1.

1. #include<stdio.h>  
2. int main(){    
3. int i=1;      
4. do{    
5. printf("%d \n",i);    
6. i++;    
7. }while(i<=10);   
8. return 0;  
9. }     

Output

1
2
3
4
5
6
7
8
9
10

Program to print table for the given number using do while loop

1. #include<stdio.h>  
2. int main(){    
3. int i=1,number=0;    
4. printf("Enter a number: ");    
5. scanf("%d",&number);    
6. do{    
7. printf("%d \n",(number*i));    
8. i++;    
9. }while(i<=10);    
10. return 0;  
11. }    

Output

Enter a number: 5
5
10
15
20
25
30
35
40
45
50

Enter a number: 10
10
20
30
40
50
60
70
80
90
100

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Infinitive do while loop

The do-while loop will run infinite times if we pass any non-zero value as the conditional expression.

1. do{  
2. //statement  
3. }while(1);