Editing Global variable (section)

{{Short description|Computer programming, a variable accessible throughout a computer program}}
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In [[computer programming]], a '''global variable''' is a variable with global [[scope (programming)|scope]], meaning that it is visible (hence accessible) throughout the program, unless [[Variable shadowing|shadowed]]. The set of all global variables is known as the ''global environment'' or ''global state.'' In [[Compiled language|compiled languages]], global variables are generally [[static variable]]s, whose [[Variable (programming)#Scope and extent|extent]] (lifetime) is the entire runtime of the program, though in [[Interpreted_language|interpreted languages]] (including [[command-line interpreter]]s), global variables are generally dynamically allocated when declared, since they are not known ahead of time.

In some languages, all variables are global, or global by default, while in most modern languages variables have limited scope, generally [[lexical scope]], though global variables are often available by declaring a variable at the top level of the program. In other languages, however, global variables do not exist; these are generally [[modular programming]] languages that enforce a module structure, or [[class-based programming|class-based]] [[object-oriented programming language]]s that enforce a class structure.