When and Why Use the Scope Resolution Operator (::) Without a Scope in C ?

Scope Resolution Operator Usage Without Scope

In C , the scope resolution operator (::) allows access to global members or members of a namespace even when there is no scope present. When used without a scope, as in the example ::foo(), it signifies global scope.

Purpose

The scope resolution operator used without a scope has the following purposes:

• Global Member Access: It provides access to global functions, variables, and classes without specifying their namespace or class name. This is useful when multiple functions or variables with the same name exist in different namespaces or classes and you need to access the global one.
• Name Conflict Resolution: If there is a function or variable name conflict within the current scope, using :: will ensure that the global member is accessed instead of the local one.

Example

Consider the following example:

void bar(); // global function

class foo {
    void some_func() { ::bar(); } // calls global bar(), not class version
    void bar(); // class member
};

In this example, if we want to call the global bar() function from within the class member function some_func(), we need to use ::bar() to explicitly specify the global scope. Otherwise, it would attempt to call the class member bar().

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