Compilation error: "stddef.h: No such file or directory"

Question

Whenever I try to compile this code it always ends up with this error:

    In file included from /usr/include/wchar.h:6:0,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/cwchar:44,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/bits/postypes.h:40,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/iosfwd:40,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/ios:38,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/ostream:38,
             from /usr/lib/gcc/i686-pc-cygwin/4.9.2/include/c++/iostream:39,
             from test.cpp:1:
    /usr/include/sys/reent.h:14:20: fatal error: stddef.h: No such file or directory
    #include <stddef.h>
                ^
    compilation terminated.

The code I was trying to compile is:

#include <iostream>
using namespace std;

int main()
{
    cout << "Hello World! :D";
    return 0;
}

Answer 1

The error is because your gcc-core package and gcc-g++ are not of the same version. Either downgrade one of them to solve the problem or update both the libraries. Updating both the libraries is the recommended way.