Exercício 10 - Strings

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

main()
{
      char b[50],min[50];
      int i,l;

      printf("Digite alguma frase:");
      gets(b);

      for(i=0; b[i] != '\0'; i++)
      {
               min[i] = tolower(b[i]);
               if((b[i] == 'a') || (b[i] == 'e') || (b[i] == i) || (b[i] == 'o') || (b[i] == 'u'))
               {
                    if(min[i] != 0)
                    {
                          b[i]= min[i] = toupper(b[i]);
                    }
                    else
                    {
                        b[i]=tolower(b[i]);
                    }
               }
      }
      printf("Vogal/Vogais invertidas: \n");
      puts(b);
      system("Pause");
}