Any way to read big endian data with little endian program?

Question

An external group provides me with a file written on a Big Endian machine, and they also provide a C++ parser for the file format.

I only can run the parser on a lit

Answer 1

the best approach is to just define the endianess in the file format, and not say it's machine dependent. the writer will have to write the bytes in the correct order regardless of the CPU it's running on, and the reader will have to do the same.

Answer 2

Back in the early Iron Age, the Ancients encountered this issue when they tried to network primitive PDP-11 minicomputers with other primitive computers. The PDP-11 was the first little-Endian computer, while most others at the time were big-Endian.

To solve the problem, once and for all, they developed the network byte order concept (always big-Endia), and the corresponding network byte order macros ntohs(), ntohl(), htons(), and htonl(). Code written with those macros will always "get the right answer".

Lean on your external supplier to use the macros in their code, and the file they supply you will always be big-Endian, even if they switch to a little-Endian machine. Rewrite the parser they gave you to use the macros, and you will always be able to read their file, even if you switch to a big-Endian machine.

A truly prodigious amount of programmer time has been wasted on this particular problem. There are days when I think a good argument could be made for hanging the PDP-11 designer who made the little-Endian feature decision.