When does an c/c++ project need a configure file?

Question

Almost every c/c++ open source project I see ships with it a configure file.

But in our own c/c++ project I haven't seen this file so far,

when is it needed?

Answer 1

I think you are speaking about configure script which is used, when autotools are used to build the project.

The main purpose of the configure file is to generate Makefiles appropriate to your system configuration and to check various preconditions (installed libs, for example).