#include <iostream>
using namespace std;

static const int MAXLEN = 11;

// rather than side-effect of changing input string,
// we use a local variable. so the returned string is changed.
// so don't bother storing return values without copying them elsewhere.
char *cStringtoUpper(const char *lower)
{
    static char upper[MAXLEN+2];
    int i = 0;

    while (lower[i] != 0)
    {
        if (lower[i] >= 'a' && lower[i] <= 'z')
            upper[i++] = lower[i] - 0x20;
        else
            upper[i++] = lower[i];
    }

    // dont forget to null terminate the new string!
    upper[i] = 0;

    return upper;
}

int main()
{
    int i;
    char line[MAXLEN+2];

    cout << "This program will convert strings up to " << MAXLEN <<
        " characters of length into uppercase.\n" <<
        "You may exit by inputting 'Q' (in uppercase!)\n\n";

    while (1)
    {
        cout << "Enter string: ";

        cin.get(line, MAXLEN+1);

        cin.ignore();   // strip the '\n'

        // easy check for quit. make sure it's Q alone!
        if (line[0] == 'Q' && line[1] == 0)
            break;

        cout << "In uppercase: " << cStringtoUpper(line) << endl;
    }

    cout << "\nGoodbye!\n\n";

    // signals success to executing environment.
    return 0;
}