Only numeric

Please be patient with this student who does not know the answer to this simple question

I have a program prompting the user for a numeric input between a range of numbers.

I figured out how to test the number but need to know how to limit entry to numeric numbers only!

Or test the entry to see if is non-numeric (alpha characters)

HELP!!

There's a function called isalpha() which will check if a character is alphabetic. There's another one called isalnum() which will check if a character is alphanumeric.

I think they're in ctype.h.