ex13.5.c

#include <stdio.h>

int main(int argc,char*argv[])
{
  if (argc!=2)
  {
    printf("ERROR:You need one argument.\n");
    // this is how you abort a program
    return 1;
  }

  int i=0;
  for(i=0;argv[1][i]!='\0';i++)
  {
    char letter=argv[1][i];

    switch (letter)
    {
      case 'a':
      case 'A':
        printf("%d:'A'\n", i);
        break;

      case 'e':
      case 'E':
        printf("%d:'E'\n", i);
        break;

      case 'i':
      case 'I':
        printf("%d:'I'\n", i);
        break;

      case 'o':
      case 'O':
        printf("%d:'O'\n", i);
        break;

      case 'u':
      case 'U':
        printf("%d:'U'\n", i);
        break;

      case 'y':
      case 'Y':
        if(i>2)
        {
          // it's only sometimes Y
          printf("%d:'Y'\n", i);
        }
        break;



      default:
        printf("%d:%c is not a vowel\n", i,letter);
    }
  }
  return 0;
}