C Program: Count the Number of Vowels in a String

In this tutorial, we will write a C program to find/count the number of vowels in a given string.

The vowels, a, e, i, o, u, could either be in lowercase or uppercase; the program will find/count them both.

c program count vowels in a string

Here is the program. Inside the while loop, the if condition checks for both lowercase and uppercase vowels. If the condition is met, the vowels variable is incremented. Also, the printf() statement prints the vowel inside the condition.

				#include <stdio.h>

				int main() {
					unsigned short count = 0, vowels = 0;
					char str[100], c;

					printf("Enter a string: ");
					scanf("%[^\n]", str);

				   	while(str[count] != '\0') {
				   	  c = str[count];
				   	  if(c == 'a' || c == 'A' || c == 'e' || c == 'E' || c == 'i' || c == 'I' 
				   	  	|| c == 'o' || c == 'O' || c == 'u' || c == 'U') {
				   	  	printf("%c", c);


				   	printf("NUMBER OF VOWELS: %hu \n", vowels);

					return 0;

On running the program, the prompt to enter a string will appear. Enter some string.

					$ ./a.out
					Enter a string: POWERFUL YOU HAVE BECOME

The output of the above string - POWERFUL YOU HAVE BECOME - is as follows:

c program find vowels output