What is the difference between typedef and define in the C language?

Typedef and #define are both keywords used to create type aliases or macro definitions, but there are some differences between them.

1. declaration of a data type
2. a type definition

typedef int Integer;  // 创建一个类型别名 Integer，表示 int 类型
Integer num = 10;     // 使用 Integer 替代 int

1. define
2. Create a definition for.

#define PI 3.14159     // 定义一个常量 PI
float area = PI * r * r;  // 使用 PI 替代 3.14159

In summary, typedef is used to create type aliases, while #define is used to create macro definitions. typedef creates a new type name, while #define creates a text replacement.