How static libraries work? (C/C++)

I know how to use and create them, but I can't find a text about how it is implemented, how开发者_如何学C function call happens and so on, can someone help me with that information? Because I want to understand them, but not just know what is it and how it is working

As you may know, when you compile a source file you get an object file. Depending on your platform its extension may be .o or .obj or anything else. A static library is basically a collection of object files, kind of like a .zip file but probably not compressed. The linker, when trying to generate an executable tries to resolve the referenced symbols, i.e. locate in which object file (be it in a library or otherwise) they are defined and links them together. So, a static library may also contain an index of defined symbols in order to facilitate this. Exact implementation depends on the specific linker and library file format but the basic architecture is as mentioned.

You may want to check the italicized keywords in Wikipedia or something for more info on them.

I think wikipedia explains it well:

In computer science, a static library or statically-linked library is a set of routines, external functions and variables which are resolved in a caller at compile-time and copied into a target application by a compiler, linker, or binder, producing an object file and a stand-alone executable. This executable and the process of compiling it are both known as a static build of the program. Historically, libraries could only be static. Static libraries are either merged with other static libraries and object files during building/linking to form a single executable, or they may be loaded at run-time into the address space of the loaded executable at a static memory offset determined at compile-time/link-time.

A static library is purely a collection of .o files, put together in an archive that's something like a zip file (with no compression). When you use it for linking, the linker will search the library for .o files that provide any of the missing symbols in the main program, and pull in those .o files for linking, as if they had been included on the command line like .o files in your main program. This process is applied recursively, so if any of the .o files pulled in from the library have unresolved symbols, the library is searched again for other .o files that provide the definitions.