While mixing C and C++ code, how to avoid name mangling done by C++ compiler for C Code

C language does not have overloading, that's why C  function names are not mangled by C compiler (such as GCC), but C++ has overloading. Overloading means the same function name can appear for more than two functions in C++ with different parameters. That's why C++ complier do name mangling to identify the function names uniquely. 

You may encounter a problem while writing you own library by mixing C and C++ code. because you  have to compile it with C++ compiler and it will mangled the function names. If you want to avoid the mangling of function names done by C++ compiler then you can use extern "C" keyword in the code. This will tell C++ compiler that do not mangled function names, variable names, defined in extern "C" brackets.

For example:

extern "C"
{
   int functionx();
}

The name of functionx will not be get mangled by C++ compiler.