How to use const in c++

const in C is used to declare immutable data, that is, constants, ensuring that variables or objects cannot be modified after declaration, improving data integrity, improving code readability, and allowing compiler optimization. The main uses include: 1. Ensure data integrity; 2. Improve code readability; 3. Optimize compiler optimization.

Usage of const in C

In C, the const keyword is used to specify immutable data. It is a constant modifier that when used with a variable or object type, the variable or object can no longer be modified.

Syntax

const <type> <variable_name> = <value>;

• <type>: The type of the constant to be declared.
• <variable_name>: The name of the constant.
• <value>: The value of the constant (optional).

Purpose

The main purpose of using const is:

• Ensure data integrity: Constant Guarantees that the initial value of a variable or object remains unchanged throughout the execution of a program, thus preventing accidental modification.
• Improve code readability: By explicitly marking constants, you can improve code readability and understandability.
• Optimizing Compiler Optimization: The compiler can optimize code involving constants because their values ​​are known and will not change.

Usage Rules

• const A variable or object must be initialized when defined.
• Once declared, the type and value of a const variable or object cannot be changed.
• const An object can only call its const member functions, that is, functions that do not modify the object itself.
• const variables can be used like ordinary variables, but they cannot be reassigned.

Notes

• # The const keyword can be used with other modifiers such as static and volatile.
• const can only guarantee that the internal state of a variable or object will not change, but it does not guarantee that the pointer pointing to it will not be modified.
• const objects can contain mutable members, but these members can only be modified through const member functions.

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