The do-while loop in C is a control flow statement that executes a block of code repeatedly until a specified condition becomes false. Unlike the while loop, the do-while loop guarantees the execution of the block of code at least once, regardless of the condition's initial evaluation.
The do-while loop is particularly useful when you need to execute a block of code at least once and then repeat it based on a condition. It's commonly used when you want to perform an action and then check a condition for continuing the loop.
do {
// Statements to be executed
} while (condition);
#include <stdio.h>
int main() {
int i = 1;
do {
printf("Count: %d\n", i);
i++;
} while (i <= 5);
return 0;
}
Count: 1 Count: 2 Count: 3 Count: 4 Count: 5
#include <stdio.h>
int main() {
int num;
do {
printf("Enter a positive number: ");
scanf("%d", &num);
} while (num <= 0);
printf("You entered: %d\n", num);
return 0;
}
Enter a positive number: -8 Enter a positive number: -6 Enter a positive number: 4 You entered: 4
#include <stdio.h>
int main() {
char choice;
do {
printf("Menu:\n");
printf("1. Option 1\n");
printf("2. Option 2\n");
printf("3. Exit\n");
printf("Enter your choice: ");
scanf(" %c", &choice);
switch (choice) {
case '1':
printf("Option 1 selected\n");
break;
case '2':
printf("Option 2 selected\n");
break;
case '3':
printf("Exiting...\n");
break;
default:
printf("Invalid choice. Please try again.\n");
}
} while (choice != '3');
return 0;
}
Menu: 1. Option 1 2. Option 2 3. Exit Enter your choice: 2 Option 2 selected Menu: 1. Option 1 2. Option 2 3. Exit Enter your choice: 1 Option 1 selected Menu: 1. Option 1 2. Option 2 3. Exit Enter your choice: 3 Exiting...
#include <stdio.h>
int main() {
char user_choice;
int number;
do {
printf("Enter a number: ");
scanf("%d", &number);
printf("Square of %d is %d\n", number, number * number);
printf("Would you like to enter another number? (y/n): ");
fflush(stdin); // Clear input buffer
scanf(" %c", &user_choice); // Notice the space before %c to consume the newline character
} while (user_choice == 'y');
return 0;
}
Enter a number: 5 Square of 5 is 25 Would you like to enter another number? (y/n): y Enter a number: 2 Square of 2 is 4 Would you like to enter another number? (y/n): n
#include <stdio.h>
int main() {
char str[100];
int count = 0, i = 0;
printf("Enter a string: ");
scanf("%s", str);
do {
count++;
i++;
} while (str[i] != '\0');
printf("Number of characters: %d\n", count);
return 0;
}
Enter a string: Program Number of characters: 7
#include <stdio.h>
int main() {
int num, factorial = 1, i = 1;
printf("Enter a number: ");
scanf("%d", &num);
do {
factorial *= i;
i++;
} while (i <= num);
printf("Factorial of %d = %d\n", num, factorial);
return 0;
}
Enter a number: 5 Factorial of 5 = 120
#include <stdio.h>
int main() {
int n, first = 0, second = 1, next, i = 1;
printf("Enter the number of terms: ");
scanf("%d", &n);
printf("Fibonacci Series: ");
do {
printf("%d ", first);
next = first + second;
first = second;
second = next;
i++;
} while (i <= n);
return 0;
}
Enter the number of terms: 8 Fibonacci Series: 0 1 1 2 3 5 8 13
#include <stdio.h>
int main() {
int n, i = 2;
printf("Enter the upper limit: ");
scanf("%d", &n);
printf("Prime numbers between 2 and %d are: ", n);
do {
int is_prime = 1, j = 2;
while (j <= i / 2) {
if (i % j == 0) {
is_prime = 0;
break;
}
j++;
}
if (is_prime)
printf("%d ", i);
i++;
} while (i <= n);
return 0;
}
Enter the upper limit: 10 Prime numbers between 2 and 10 are: 2 3 5 7