C Source Code/Count the number of vowels in a word

Introduction

Each time you see a vowel, add one. For example:

because.

b (no) e (+1=1) c (no) a (+1=2) u (+1=3) s (no) e (+1=4)

One way of doing this is to scan the string "because" from left to right. We read in a character, and check if it is a vowel. The character is compared to a dictionary of vowels. This "dictionary" is stored in the line

   static const char vowels[] = "aeiouAEIOU";

so in this code, the lowercase and uppercase letters are all vowels.

The code

#include <stdio.h>
#include <string.h>

/* main: main loop for counting vowels in word */
int main(void)
{
    size_t i, j, word_len, vowels_len;
    int vowel_count;
    char word[21];   /* 20 + '\0' */
    static const char vowels[] = "aeiouAEIOU";

    printf("Enter a word: ");
    scanf("%20s", word);

    /* initialise variables */
    word_len   = strlen(word);     
    vowels_len = strlen(vowels);
    vowel_count = 0;

    for (i = 0; i < word_len; ++i) {         /* loop through word   */
        for (j = 0; j < vowels_len; ++j) {   /* loop through vowels */
           if (word[i] == vowels[j]) {
               ++vowel_count;
               break;
           }
        }
    }

    printf("\nThe no. of vowels in '%s' is %d\n", word, vowel_count);

    /* indicate success */
    return 0;
}

Line by line explanation

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