Convert a String In C++ To Upper Case

Question

How could one convert a string to upper case. The examples I have found from googling only have to deal with chars.

Answer 1

template
char* toupper(char (&dst)[size], const char* src) {
    // generate mapping table once
    static char maptable[256];
    static bool mapped;
    if (!mapped) {
        for (char c = 0; c < 256; c++) {
            if (c >= 'a' && c <= 'z')
                maptable[c] = c & 0xdf;
            else
                maptable[c] = c;
        }
        mapped = true;
    }

    // use mapping table to quickly transform text
    for (int i = 0; *src && i < size; i++) {
        dst[i] = maptable[*(src++)];
    }
    return dst;
}