How are constants defined in the C programming language?

In the C language, the #define preprocessor directive can be used to define constants. Constants are named following the same rules as variables, typically using uppercase letters.

The syntax for defining constants is as follows:

#define 常量名 常量值

For example, defining an integer constant MAX_NUM as 100.

#define MAX_NUM 100

In the program, you can directly use the constant name MAX_NUM to represent the constant value of 100.

In addition, the C language also provides the const keyword to define constants. Constants defined using the const keyword are typically used within functions, and the syntax for defining them is as follows:

const 数据类型 常量名 = 常量值;

For example, define an integer constant MAX_VALUE as 100.

const int MAX_VALUE = 100;

Constants defined using the const keyword have a scope limited to the block in which they are defined (blocks can be functions, loops, conditional statements, etc.).