How to define global variables in the C language?

Global variables in C language can be defined outside of any function. The definition of a global variable follows the following format:

数据类型 变量名;

For example, you can define a global variable of type integer using the following code:

int globalVariable;

After defining a global variable, it can be used anywhere in the program, including inside and outside functions. If you want to use a global variable in different source files, you just need to declare it in the source file where it is needed using the extern keyword. For example, to define a global variable globalVariable in one source file and use it in another, follow these steps:

1. external

extern int globalVariable;

1. Define the global variables in the source file where they are declared.

int globalVariable;

In this way, global variables can be used by including the header file containing them in other source files. It is important to note that the definition and declaration of global variables should ideally be placed in the header file and included in the source files where the global variable is needed. This can improve the readability and maintainability of the code.