Unlike the for and while loop, which test the loop condition at the top of the loop, but the do-while loop in C programming, checks its condition at the bottom of the loop.
With above statement, it means that the do-while loop always executes at least once, unlike the other two loops.
So, do-while loop is generally used in menu-driven program like Calculator Program, which gives options to the user whether he/she wants addition, subtraction, multiplication, etc. to perform the desired action accordingly. Following example illustrates the concept of do-while loop.
Here is an example program based on do-while loop in C programming.
/* C do-while Loop Example
* This program illustrates the
* concept of do-while loop in C
*/
#include<stdio.h>
#include<dos.h>
#include<conio.h>
void main()
{
char choice;
struct date d;
getdate(&d);
clrscr();
do
{
printf("1. Good News\n");
printf("2. Bad News\n");
printf("3. Today's Date\n");
printf("4. Exit\n");
printf("Enter your choice (1-4) : ");
scanf("%c", &choice);
switch(choice)
{
case '1' :
printf("You have chosen right language.");
break;
case '2' :
printf("You have to learn a lot");
break;
case '3' :
printf("Today's Date : %d/%d/%d", d.da_day, d.da_mon, d.da_year);
break;
case '4' :
exit(1);
default :
printf("Wrong choice..!!\n");
}
printf("\n\n");
}while(choice!=4 && choice!=getchar());
getch();
}
Here is the 2 sample run of this do-while loop example program in C.
To print date in words in C language, refer print date in words.