Can not find bsearch(vc2008) even include the header file

Question

I maintain an old project and encountered some linker errors.

The error message is:
error LNK2019: unresolved external symbol __imp__bsearch referenced in function "bool __cdecl is_sync_host

As far as I know, the bsearch function is included in the header file "cstdlib" or "stdlib.h", but even if I include the header, I can't find "bsearch".

I suspect this is due to the fact that this old project ignores some lib because of symbol conflicts (I also don't know why they prefer to omit the lib instead of renaming the functions)

The ignored libs : msvcrt.lib;msvcrtd.lib;libcmt.lib;libc.lib

I try to add those ignored libs back, but then I encounter a lot of "symbol redefinition" problems and I don't think that renaming those functions is an applicable solution.

I found a work around (replace the bsearch to std::binary_search), but I want to know why and how to solve this problem properly (how comes the compiler can't find the bsearch?). Thanks.

Answer 1

error LNK2019:

This is a linker error. Your code compiled just fine (.c > .o), it is the linking that gives you problems (.o > .exe).

The ignored libs : "msvcrt.lib;msvcrtd.lib;libcmt.lib;libc.lib"

This means the code is ignoring the C standard library, so no wonder it doesn't find the standard bsearch() function...

The question is, why? There is simply no reason (that I could think of) for well-written code to explicitly ignore the standard library.

I try to add those ignored libs back, but then I meet a lot of "symbol redefinition" problems...

Which brings me to the conclusion that your code is not "well-written", at which point it is very difficult to give advice without seeing the code, or telling you to "ditch it, it's crap". ;-)

I don't think that rename those functions is an applicable solution.

If you have functions in your project that are named like standard library functions, unless your project is a standard library, they are misnamed and should be renamed.

But at this point, I would really like to see the code in question to figure out what the original programmer might have had in mind...