[Solved] C++ How do you make every third letter of a char array into an uppercase letter? [closed]

while (aPhrase[i]) {
    c = aPhrase[i];
    if (isVowel(c)) 
        c="!";
    else if ((i % 3) == 0)
        c = toupper(c);
    putchar(c);
    ++i;
}