This is just a practice test I found online to prepare for a class that starts on the 27th. Most of the questions I can find on google but this one has stumped me.
The expression !isdigit(ch) evaluates to nonzero if ch is ________.
A) an alphabetic character
D) both A and C
E) None of the above
Do you know what isdigit() does with its argument? And what it returns?