#include<stdio.h>
#include<string.h>
                                   
void uppercase(char string[]);     
                                  
int main(void) { 
  char vowels[6]; 
                  
  strcpy(vowels, "aeiou");
  printf("%s\n", vowels); 
                          
  uppercase(vowels);
  
  printf("%s\n", vowels);

  return 0;
}

// alt.: declare as char *string
void uppercase(char string[]) {
  int i = 0;
  while (string[i] !='\0') {
    string[i] = string[i] 
                - 'a' + 'A';
    i++;
  }
}