Question

I have the following code:

#ifndef GOOGLESET_PHP_H
#define GOOGLESET_PHP_H 
zend_class_entry *googleset_ce;
#endif /* GOOGLESET_PHP_H */

For some reason if I include this header file in more than one cpp file, the compiler shouts that I am declaring googleset_ce more than once. Shouldn’t the conditional macros above be enough to avoid this?

Answer 1

You need to use the extern keyword:

#ifndef GOOGLESET_PHP_H
#define GOOGLESET_PHP_H

extern zend_class_entry * googleset_ce;

#endif // GOOGLESET_PHP_H

Otherwise the compiler thinks you are declaring the variable in every file that includes this header.

This is one reason global variables are frowned upon.