Whether or not c is a punctuation character. That includes all ASCII characters which are not control characters, letters, digits, or whitespace.
1 assert( isPunctuation('.')); 2 assert( isPunctuation(',')); 3 assert( isPunctuation(':')); 4 assert( isPunctuation('!')); 5 assert( isPunctuation('#')); 6 assert( isPunctuation('~')); 7 assert( isPunctuation('+')); 8 assert( isPunctuation('_')); 9 10 assert(!isPunctuation('1')); 11 assert(!isPunctuation('a')); 12 assert(!isPunctuation(' ')); 13 assert(!isPunctuation('\n')); 14 assert(!isPunctuation('\0')); 15 16 // N.B.: Non-ASCII Unicode punctuation characters are not recognized. 17 assert(!isPunctuation('\u2012')); // (U+2012 = en-dash)