A singleton example in C.

main.c

#include "uSingleton.h" /* uSingleton */

extern signed int main( void ) { return uSingleton.Method_( 0 ); }

uSingleton.c

#include "uSingleton.h" /* uSingleton */

static signed int xMethod_( const signed int Arg ) { return Arg; }

const struct uSingleton uSingleton = { xMethod_ };

uSingleton.h

#if !__STDC__
# error A standard C compiler is required!
#elif defined(uSingleton)
#else
# define uSingleton uSingleton

extern const struct uSingleton { signed int (*const Method_) ( signed int Arg ); } uSingleton;

#endif