// struct person 类型(相当于 int、double等 用来开辟 空间)
struct person {
int age;
char *name;
};
// struct(是指类型),定义一个变量(first)
struct person first;
struct person *ptr;
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// (每次创建) struct(是指类型),定义一个变量(yj1)
struct yuangong yj1 = {};