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C Academy · Lesson

Building Char Utilities

Practical examples.

Combining What You Know

Now you can build small, practical character utilities by combining char arithmetic, the ctype library, and string loops.

Let us write a few common helpers.

#include <stdio.h>
#include <ctype.h>

int main(void) {
    char c = 'g';
    printf("Upper: %c\n", toupper(c));
    return 0;
}

Counting Vowels

A vowel counter checks each character against the set a, e, i, o, u in either case.

#include <stdio.h>
#include <ctype.h>

int count_vowels(const char *s) {
    int n = 0;
    for (int i = 0; s[i]; i++) {
        char c = tolower(s[i]);
        if (c=='a'||c=='e'||c=='i'||c=='o'||c=='u') n++;
    }
    return n;
}

int main(void) {
    printf("%d\n", count_vowels("Education"));
    return 0;
}

All lessons in this course

  1. Characters as Integers
  2. The ctype Library
  3. Reading Characters
  4. Building Char Utilities
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