static functions

static functions are functions that are only visable to other functions in the same file. Consider the following code.

main.c
#include main() { Func1(); Func2(); }

funcs.c

/************************************* * * Function declarations (prototypes). * *************************************/ /* Func1 is only visable to functions in this file. */ static void Func1(void); /* Func2 is visable to all functions. */ void Func2(void); /************************************* * * Function definitions * *************************************/ void Func1(void) { puts("Func1 called"); } /*************************************/ void Func2(void) { puts("Func2 called"); }

If you attempted to compile this code with the following command,

   gcc main.c funcs.c   

it will fail with an error simular to.....

   undefined reference to `Func1'  

Because 'Func1' is declared as static and cannot be 'seen' by 'main.c'.

Notes:

For some reason, static has different meanings in in different contexts.

1. When specified on a function declaration, it makes the function local to the file.

2. When specified with a variable inside a function, it allows the vairable to retain its value between calls to the function. See static variables.

It seems a little strange that the same keyword has such different meanings....

See Also:

static variables

C++ extensions for static