#+include+<+stdio+.+h+> +union+student+ +int+num+; +char+name+[20]; +int+age+; }; +int+main+(){ +uni

#include <stdio.h>

union student {
    int num;
    char name[20];
    int age;
};

int main() {
    union student stu;
    stu.num = 123;
    printf("num: %d\n", stu.num);
    
    strcpy(stu.name, "John");
    printf("name: %s\n", stu.name);
    
    stu.age = 20;
    printf("age: %d\n", stu.age);
    
    return 0;
}

输出结果：

num: 123
name: John
age: 20