Well there are many zlib articles , tips and tutorials. Some of them are

1) Bobobobo's Blog

This article basically tells you how to use zlib, and there is a snippet of code that will get you going.

This project shows you how to use zlib. Its a console project, because there's no need to create a window to demonstrate use of zlib.

2) zlib: Add Industrial Strength Compression to Your C/C++ Apps

For simplicity's sake, this tutorial covers only the basic C-style interface. All the concepts inherent there will be relevant to most other bindings.

Since its in C language, it will be most beneficial to your requirements.

Last, you can use this too available in zlib. From the manual, Utility Functions:

ZEXTERN int ZEXPORT uncompress OF((Bytef *dest, uLongf *destLen,
                                   const Bytef *source, uLong sourceLen));

If you had looked at zlib.h, you would have found very near the top:

#ifdef __cplusplus
extern "C" {
#endif

(and a corresponding close brace near the bottom).