What does ::and: mean in c++

In C, :: (scope resolution operator) is used to access global variables, static members and specified namespaces, while :: (member access operator) is used to access members of a class or structure .

The meaning of :: and: in C

In C programming, :: and: are both operations symbols, respectively representing different meanings:

:: (scope resolution operator)

• Access global or static member variables and functions
• Specify the namespace of a class or object
• Reference hidden or overloaded names

Example:

<code class="cpp">int x; // 全局变量

class MyClass {
public:
    int y; // 成员变量
    void print() {
        cout << MyClass::x << " " << y; // 访问全局变量和成员变量
    }
};</code>

: (Member access operator)

• Access class or structure member variables or functions
• Members pointing to objects
• Indirect access pointer members

Example:

<code class="cpp">struct Point {
    int x;
    int y;
};

Point p;
p.x = 10; // 访问成员变量</code>

Summary

:: Used to access members in different namespaces or classes , while: is used to access members of a class. These two operators are very important in C, and understanding them is crucial to writing efficient code.

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