A static member variable is declared in a class. Where is the static member variable defined?

A static member variable is a specific type of variable in a class, which belongs to the class itself rather than any individual instance of that class. As a result, all instances of the class share the same copy of the static variable.

Static member variables are declared within the class definition, outside of any member functions. The keyword 'static' is used to indicate that the variable is a static member. For example, in C++, the declaration would look like this: ```cpp class MyClass { public: static int myStaticVariable; }; ```

Unlike regular member variables, which are defined and initialized within the class definition, static member variables need to be explicitly defined and initialized outside of the class definition, in the global scope. This is because they are not tied to any specific instance of the class and must have a single, unique definition. In C++, this definition is usually done in the source (".cpp") file corresponding to the header (".h") file where the class is defined. The definition should provide the scope resolution operator `::` to indicate that the static variable belongs to the class. Here's an example: ```cpp // MyClass.cpp #include "MyClass.h" int MyClass::myStaticVariable = 0; // Define and initialize the static variable ``` This definition must be done only once in the program's source code to avoid multiple definition errors.

Static member variables can be accessed either through an instance of the class or directly through the class name. Here's an example: ```cpp int main() { // Access through an instance MyClass obj; obj.myStaticVariable = 5; // Access through the class name MyClass::myStaticVariable = 10; } ``` Both of these access methods will set the same static variable's value, as it is shared among all instances of the class.