The role of :: in c++

:: is the scope resolution operator in C, used to access identifiers in the global scope, namespace or class. Global variables, identifiers in a namespace, and member functions or static members of a class can be accessed through the :: operator.

In C:: The role of

Answer:
In C , :: is a scope resolution operator used to access identifiers in the global scope.

Detailed description:

Global scope

• In C program, everything is not in any function or class Declared identifiers belong to the global scope.
• Identifiers in the global scope can be accessed through the :: operator.

Example:

<code class="cpp">int globalVariable = 10; // 全局变量

int main() {
  // 使用 :: 访问全局变量
  std::cout << ::globalVariable << std::endl; // 输出 10
  return 0;
}</code>

Namespace

• :: Also Can be used to access identifiers in a namespace.
• Namespaces are used to organize code and avoid name conflicts.

Example:

<code class="cpp">namespace myNamespace {
  int num1 = 1;
}

int main() {
  // 使用 :: 访问名称空间中的标识符
  std::cout << myNamespace::num1 << std::endl; // 输出 1
  return 0;
}</code>

Class name space

• :: It can also be used within a class to access member functions or static members of the class.

Example:

<code class="cpp">class MyClass {
public:
  static void print() {
    std::cout << "Hello from MyClass" << std::endl;
  }
};

int main() {
  // 使用 :: 访问类成员函数
  MyClass::print(); // 输出 "Hello from MyClass"
  return 0;
}</code>

Note:

• :: Operation The operator can only be used to access identifiers, not expressions or statements.
• In the global scope, you can use :: to refer to itself (that is, :: is equivalent to this).

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