You copied the Doc URL to your clipboard.

C++ and C libraries and the std namespace

All C++ standard library names, including the C library names, if you include them, are defined in the namespace std using the following C++ syntax:

#include <cstdlib> // instead of stdlib.h

This means that you must qualify all the library names using one of the following methods:

  • specify the standard namespace, for example:

  • use the C++ keyword using to import a name to the global namespace:

    using namespace std;
  • use the compiler option --using_std.


errno is a macro, so it is not necessary to qualify it with a namespace.

See also


Compiler Reference: