toggle_case.c

/*
 * Toggles character case
 *
 * e.g in: 'b' -> out: 'B'
 *     in: 'B' -> out: 'b'
 *     in: '5' -> out: '5'
 *
 * @param c ascii character to be toggled
 * @return toggled ascii character if alphabetical,
 *      otherwise intact value of c
 */
int
toggle_case(int c)
{
    if(c >= 'A' && c <= 'Z')
        return c + 'a' - 'A';
    else if(c >= 'a' && c <= 'z')
        return c - ('a' - 'A');
    else
        return c;
}