Function letter

src/hacklib.c:68–72

is 'c' a letter? note: '@' classed as letter */

/* is 'c' a letter?  note: '@' classed as letter */
boolean
letter(char c)
{
    return (boolean) ('@' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}

/* force 'c' into uppercase */
char