Fixed length of number read in fscanf()?

Question

C++ / C#

This thing reads a number of length no more than 2 And I need it to read only and only numbers, length exactly 2, how to do this? For example, she does not count the number 1, but 01 counts
fscanf(f, "%2u ", &ulong)

Answer 1

Here they said that you can use % n to control the number of characters read, but in general you need to read a string and parse it already.