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32-bit compilers emit, respectively: _f _g@4 @h@4 In the stdcall and fastcall mangling schemes, the function is encoded as _name@X and @name@X respectively, where X is the number of bytes, in decimal, of the argument(s) in the parameter list (including those passed in registers, for fastcall).
The static keyword (static and extern are mutually exclusive), applied to the definition of an external variable, changes this a bit: the variable can only be accessed by the functions in the same module where it was defined. But it is possible for a function in the same module to pass a reference (pointer) of the variable to another function ...
In Python, if a name is intended to be "private", it is prefixed by one or two underscores. Private variables are enforced in Python only by convention. Names can also be suffixed with an underscore to prevent conflict with Python keywords. Prefixing with double underscores changes behaviour in classes with regard to name mangling.
Information hiding is accomplished by furnishing a compiled version of the source code that is interfaced via a header file. Almost always, there is a way to override such protection – usually via reflection API (Ruby, Java, C#, etc.), sometimes by mechanism like name mangling ( Python ), or special keyword usage like friend in C++.
Such extern declarations are often placed in a shared header file, since it is common practice for all .c files in a project to include at least one .h file: the standard header file errno.h is an example, making the errno variable accessible to all modules in a project.
This is also valid in C++. (C++ 98/03 deprecated this usage in favor of anonymous namespaces, but is no longer deprecated in C++ 11.) Also, C++ implicitly treats any const namespace-scope variable as having internal linkage unless it is explicitly declared extern, unlike C. A name's linkage is related to, but distinct from, its scope. The scope ...
C++ generally prohibits forward references, but they are allowed in the special case of class members. Since the member function accessor cannot be compiled until the compiler knows the type of the member variable myValue, it is the compiler's responsibility to remember the definition of accessor until it sees myValue's declaration.
While a variable or function may be declared many times, it is typically defined once (in C++, this is known as the One Definition Rule or ODR). Dynamic languages such as JavaScript or Python generally allow functions to be redefined, that is, re-bound; a function is a variable much like any other, with a name and a value (the definition).