unresolved external symbol in linked library, srand48 and drand48

Question

I am working on compiling a code using Visual Studio that was previously compiled using vs10sp1 in cygwin. I am nearly finished, but I am getting 3 unresolved external symbol errors.

something like this:

libmetis.lib(util.obj) : error LNK2019: unresolved external symbol srand48 referenced in function __InitRandom

I have gathered that these symbols are in unix libraries, and are usually handled using compiler flags. And indeed upon review the source code has the flags,

  if (seed == -1) {
#ifndef __VC__
    srand48(7654321L);  
#endif
    srand(4321);  

I am using a precompiled library, and I assume it was not build with these flags. (I am compiling without cygwin). Can I link with this flag to use the functionality that I require or do I need to recompile the library?

Answer 1

You must recompile the library. Setting #if or #ifdef effectively hide code from the compiler based on those directives or defines. You cannot change the compiled code after compiling it, so it must be recompiled.