How to use const in c language

const is the keyword used to define constants in C language, ensuring that the variable value is determined at compile time and cannot be modified. Its usage includes: defining read-only variables and protecting important data from accidental modification. Specify the constant nature of function parameters or return values ​​to improve code readability and stability. The advantages of using const include: protecting data and ensuring data integrity. Improve code readability and clearly indicate the constant nature of variables or parameters. Optimizing compiler, using constant values ​​for optimization to improve code performance.

Usage of const in C language

const is a keyword in C language, used to define constant. The value of a constant is determined at compile time and cannot be modified while the program is running.

Syntax

<code class="c">const type variable_name = value;</code>

Where:

• type is the type of the variable
• variable_name is the name of the variable
• value is the value of a constant

Usage

const is mainly used in the following two situations:

1. Define read-only variables: When you need to define a data that will not change its value while the program is running, you can use const to define the data. For example:

<code class="c">const int MAX_SIZE = 100;</code>

2. Function prototype: In function prototypes, const can be used to indicate the constant nature of function parameters or return values. For example:

<code class="c">int sum(const int *arr, const int size);</code>

In this example, the parameters arr and size of the sum function are constants, and the function cannot modify their values.

Advantages

Using const has the following advantages:

• Protect data:const prevents programs from accidentally modifying important data , which improves the stability of the program.
• Improve code readability: const clearly indicates the constant nature of variables or function parameters, making the code easier to understand.
• Optimizing compiler: The compiler knows that constants will not change and can perform certain optimizations to improve code performance.

Note

• const The value of a constant must be determined at compile time.
• const constant cannot be assigned a value.
• const The memory pointed to by the pointer can be modified, but the pointer itself cannot point to other memory addresses.

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