How to use static in c++

Summary: The static keyword in C is used to declare variables, functions, and class members with static storage duration. Static variables exist throughout the entire program life cycle, static functions are limited to accessing data in the current file, and static data members are shared among all objects.

Usage of static in C

Meaning of static keyword

The static keyword in C is used to declare variables, functions and class members with static storage duration.

Variables

• Variables declared as static exist throughout the life cycle of the program.
• They are retained even if no local variables or objects refer to them.
• Static variables declared outside the class are called global static variables, and static variables declared inside the class are called static data members.

Function

• Function declared as static can only access local variables in the current file.
• They cannot access non-static data members of the class or parameters of other functions.
• They are mainly used to create utility functions that are only used in the current file.

Class members

Static data members:

• Class members declared as static are used in all shared between objects.
• They can be accessed even if the class is not instantiated.
• Usually used to store class-level variables or constants.

Static member functions:

• Member functions declared as static are not associated with a specific object.
• They can access static data members, but not non-static data members.
• is mainly used to provide common functionality in the context of a class.

Advantages of using static

• Memory optimization:Static variables and functions allocate memory at compile time, not at compile time Allocated at runtime.
• Reduce overhead: Static member functions do not require this pointer, thus reducing the overhead of function calls.
• Global access: Static data members can be accessed outside the class, which can simplify data sharing in certain situations.
• File access only: Static functions can only access data in the current file, which improves modularity and security.

Usage Precautions

• When using static, you need to pay attention to the following points:

  • Initialization of static variables must use constant expressions (i.e., cannot be determined at runtime).
  • Static functions cannot use this pointer.
  • Static data members should be used with caution because they can be shared by all objects.

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