"Scope" is a way of thinking about a variable's celebrity status: how famous is it? Scope, or visibility, refers to the extent to which your variables are known and can be referenced throughout a program. A variable with limited or small scope is known in only a small area of a program—a loop index used in only one small loop, for instance. A variable with large scope is known in many places in a program—a table of employee information that's used throughout a program, for instance.

Different languages handle scope in different ways. In some primitive languages, all variables are global. You therefore don't have any control over the scope of a variable, and that can create a lot of problems. In C++ and similar languages, a variable can be ...

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