asgn2.c

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

bool is_vowel(char arg) {
  int i;
  char vowels[] = "aeiou";
  if(arg < 91) arg += 32;
  for (i = 0; i < strlen(vowels); ++i) {
    if (arg == vowels[i]) return true;
  }
  return false;
}

void print_char(char letter) {
  if(is_vowel(letter)) {
    printf("Vowel: %c\n", letter);
  } else {
    printf("%c\n", letter);
  }
}

void print_vowels_in_word(char *word) {
  int i;
  for(i = 0; i < strlen(word); ++i) print_char(word[i]);
}

int main(int argc, char *argv[]) {
  char word[10];
  char quit[] = "exit";

  while(strncmp(word, quit, 4)) {
    print_vowels_in_word(word);
    puts("Enter a message:");
    fgets(word, 10, stdin);
  }

  return 0;
}