How to identify the file content as ASCII or binary

Question

How do you identify the file content as being in ASCII or binary using C++?

Answer 1

To check, you must open the file as binary. You can't open the file as text. ASCII is effectively a subset of binary. After that, you must check the byte values. ASCII has byte values 0-127, but 0-31 are control characters. TAB, CR and LF are the only common control characters. You can't (portably) use 'A' and 'Z'; there's no guarantee those are in ASCII (!). If you need them, you'll have to define.

const unsigned char ASCII_A = 0x41; // NOT 'A'
const unsigned char ASCII_Z = ASCII_A + 25;