The DLL file is a dynamic connection library of Windows. Unlike ordinary static connections, the DLL does not need to connect the function library to the program when the program is compiled, but when it is running, it is found to get the entry of the specified name, To call the functions provided in the DLL, the advantage of this is that as long as the DLL provides inconvenience, then its internal implementation can be upgraded, which is relatively convenient to update the version. The DLL provides an inlet function DLLMAIN. The client gets the port of the DLL through LoadLibary. This function needs to provide a DLL file name. If the file has no path, the Windows system will look for the default path (first find the system directory, then find the current directory , Also find the directory specified by the PATH variable). There are two ways to export within the DLL: one is derived by DESCDLLEXPORT, and the other is to use the DEF file definition to be derived in the latter mode, there is a .def file in the server, The file defines all the function names and serial numbers in all DLL. When the client calls, first declare a function pointer of the same original shape, then according to the handle returned by LoadLibary to get the specified function address via the getProcessAddress function, then pass the function pointer You can get what you want.
