Implicit declaration of function basename in linux

Question

i am using basename() function in my code. Where i am including

#include <unistd.h>

and when i m compiling that code with -Wall flag it shows

following warning

warning: implicit declaration of function ‘basename’

if i am writing its declaration in my code

char * basename (const char *fname);

then it does not show that warning

why this happening.?

Answer 1

You need to include <libgen.h>.

The standard says it's in libgen.h, kernel.org does so too.

Answer 2

If you look at the man page for basename:

man 3 basename

You'll see that you need to include libgen.h to get the prototype for basename (and similar function dirname):

#include <libgen.h>