What is the usage of C language union?

In C language, a union is a special data type that can store different types of data in the same memory space. The usage of unions mainly includes the following aspects:

1. Save memory space: All members in a union share the same memory space, only one member can be stored at a time. This helps save memory, especially when only one member out of multiple will be used.
2. Type coercion: Unions can be used to perform type coercion between different data types. By modifying one member, the data type within the union can be changed, thus achieving the conversion between different types of data.
3. In use for unions: A union is often used to represent a particular part of a set of related data. For example, a union can be used to represent the coordinates of a point, which includes two members representing the x-coordinate and y-coordinate.
4. Data sharing: Union allows for sharing data between different data types. By modifying a member, the data in the union can be changed, and the data can be accessed in different ways.

It should be noted that in a union, only one member’s value can be stored at a time, and modifying one member will affect the others. Therefore, caution should be taken when reading and modifying data in a union to avoid confusion or errors.