should I use fseek SEEK_END [duplicate]

Question

This question already has an answer here:

• How do you determine the size of a file in C? 14 answers

My question is simple:

Should I use fseek with SEEK_END to get to the end of a file and then get the length of it ? Because in the man it is said:

• Library implementations are allowed to not meaningfully support SEEK_END (therefore, code using it has no real standard portability).

Right now I am using stat (from C) which is better ?

Answer 1

Since C++ inherits fseek and SEEK_END from C, I'm quoting the C standard here:

C11(ISO/IEC 9899:201x) §7.21.9.2 The fseek function section 3

A binary stream need not meaningfully support fseek calls with a whence value of SEEK_END.

Answer 2

The ftell function returns a long, which means that on an ILP32 system you can't correctly get the size of a file larger than 2GB. You should use the stat function or similar to get the size of a file; check the manual for the operating system you're targeting in case you have use a different function name (stat64) or define a preprocessor macro to get the desired behavior for large files.