#include<iostream>
#include<string>

using namespace std;


//定義結構,可以同時儲存多種不同型別的資料。
struct person {
    string name;
    short age;
};

//特定位數的結構成員
struct user {
    unsigned int age : 4;//佔用4位
    bool isMan : 1;//佔用1位
};


//共用體中的資料共用相同的記憶體地址,記憶體地址的長度為最大成員的長度。
//下面的one4all，可以儲存int，long,double值，但同一時間只能儲存一種。
 

union one4all {
    int int_v;
    long long_v;
    double double_v;
};



int main() {

    //結構初始化
    person p = { "yueer",20 };
    person p1{"maomao",21};

    p.name = "fsfsdfsd";
    cout << "name=" << p.name << "  age=" << p.age << endl;
    cout << "name=" << p1.name << "  age="
 
<< p1.age << endl;

    //結構陣列
    person ps[2] = { {"aaa",20} ,{"bbb",30} };
    cout << "name=" << ps[0].name << "  age=" << ps[0].age << endl;
    cout << "name=" << ps[1].name << "  age=" << ps[1].age << endl;

    user u = { 21321
 
,true };
    cout << "age = " << u.age <<" isMan = " << u.isMan << endl;


    //共用體
    one4all o4a;
    cout << "size of one4all is " << sizeof(o4a) << endl;
    o4a.int_v = 123;
    cout << "union int_v=" << o4a.int_v << " long_v=" << o4a.long_v << " double_v=" << o4a.double_v << endl;
    o4a.long_v = 123456;
    cout << "union int_v=" << o4a.int_v << " long_v=" << o4a.long_v << " double_v=" << o4a.double_v << endl;
    o4a.double_v = 3.4455;
    cout << "union int_v=" << o4a.int_v << " long_v=" << o4a.long_v << " double_v=" << o4a.double_v << endl;

    return 0;
}

輸出結果：

name=fsfsdfsd  age=20
name=maomao  age=21
name=aaa  age=20
name=bbb  age=30
age = 9 isMan = 1
size of one4all is 8
union int_v=123 long_v=123 double_v=-9.25596e+61
union int_v=123456 long_v=123456 double_v=-9.25596e+61
union int_v=1305670058 long_v=1305670058 double_v=3.4455