12.7.1. Declare and Define Static Members
12.7.1 Declare and Define Static Members
When a class has static data members, it is not enough to declare the static member; you must also define it. For example:
class Foo { ... void method(); static int bar; };
This declaration only establishes that the class Foo
has an int
named Foo::bar
, and a member function named Foo::method
. But you still need to define both method
and bar
elsewhere. According to the ISO standard, you must supply an initializer in one (and only one) source file, such as:
int Foo::bar = 0;
Other C++ compilers may not correctly implement the standard behavior. As a result, when you switch to g++
from one of these compilers, you may discover that a p