How do you define variables in the C programming language?

In the C language, a variable is defined by first declaring the data type of the variable, and then assigning a value to it. For example:

int num; // 声明一个整型变量
num = 10; // 给变量赋值

It is also possible to assign a value while declaring a variable.

int num = 10; // 声明一个整型变量并赋值为10