Types of Loops

There are three types of loop:

• do while
• while
• for

do-while Loop also called post tested loop. This loop continues until a given condition is satisfied. This loop is used when it is necessary to execute the loop at least once

Syntax:

    do{  
    //code to be executed  
    }while(condition);  

Flowchart of do while loop

Example 1

    #include<stdio.h>  
    #include<stdlib.h>  
    void main ()  
    {  
        char c;  
        int choice,dummy;    
        do{  
        printf("n1. Print Hellon2. Print Javatpointn3. Exitn");  
        scanf("%d",&choice);  
        switch(choice)  
        {  
            case 1 :   
            printf("Hello");   
            break;  
            case 2:    
            printf("Javatpoint");  
            break;  
            case 3:  
            exit(0);   
            break;  
            default:   
            printf("please enter valid choice");      
        }  
        printf("do you want to enter more?");   
        scanf("%d",&dummy);  
        scanf("%c",&c);  
        }while(c=='y');  
    }  

After executing the above code, our output looks like

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

Example 2

    #include<stdio.h>  
    int main(){    
    int i=1;      
    do{    
    printf("%d n",i);    
    i++;    
    }while(i<=10);   
    return 0;  
    }     

The above program prints 1 to 10. After executing the above code, our output looks like

1
2
3
4
5
6
7
8
9
10

Example 3

    #include<stdio.h>  
    int main(){    
    int i=1,number=0;    
    printf("Enter a number: ");    
    scanf("%d",&number);    
    do{    
    printf("%d n",(number*i));    
    i++;    
    }while(i<=10);    
    return 0;  
    }    

After executing the above code, our output looks like

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

Infinitive do while loop

    do{  
    //statement  
    }while(1);