At runtime you may check the version of the Zlib library by accessing the following global variables.
ZLib::zlib_major, ZLib::zlib_minor and ZLib::zlib_build. These three global variables indicate the version of the zlib library that you are using. The convention that will be adhered to is that the major revision changes for major upgrades where backward compatibility is not maintained in the library. The minor number is incremented when bug fixes are added or when new features are added in such a way that it should not cause any compatibility problems (i.e. new member functions added or function parameters are added to an existing function for extended operation, but the default parameters are such that existing code should not have to change to operate as it did previously). The build number will increment for test builds and for builds where something not directly related to operation such as documentation has changed).
There are also three version related string variables ZLib::zlib_str which contains the library name and version number in human readable ASCII format (i.e. "Zlib Library version 0.1.0"), ZLib::zlib_date which contains the date when the library was compiled, and ZLib::zlib_time which contains the time of day at which the library was compiled.