结构体的处理（以c++primer plus 第六章习题4为例）

const unsigned int strsize = 50;
struct bop     //结构体就像一个数据类型如int  使用前应该先给他一个变量如本题中的bop
{
    char fullname[strsize];     // real name
    char title[strsize];        // job title
    char bopname[strsize];      // secret BOP name
    int preference;             // 0 = fullname, 1 = title, 2 = bopname
};        //如果在这里用 typedef struct bop{}bop1;     在下面初始化和传参的时候就可以将 const struct bop    变为const bop1;
void display_by_name(const struct bop *bopArray, unsigned int size)  //const 最小授权  结构体不会被改变     boparray还是一个数组   数组在传递的时候  一般用地址传递  就是指针传递     传递数组时要带上它的数组规模 
{
    for (size_t i = 0; i < size; i++)
    {
        cout << bopArray[i].fullname << endl;        //调用结构体中成员的方式
    }
}
void display_by_title(const struct bop *bopArray, unsigned int size)
{
    for (size_t i = 0; i < size; i++)
    {
        cout << bopArray[i].title << endl;
    }
}
void display_by_bopname(const struct bop *bopArray, unsigned int size)
{
    for (size_t i = 0; i < size; i++)
    {
        cout << bopArray[i].bopname << endl;
    }
}
void display_by_preference(const struct bop *bopArray, unsigned int size)
{
    for (size_t i = 0; i < size; i++)
    {
        if (bopArray[i].preference == 0)
        {
            cout << bopArray[i].fullname << endl;
        }
        else if (bopArray[i].preference == 1)
        {
            cout << bopArray[i].title << endl;
        }
        else if (bopArray[i].preference == 2)
        {
            cout << bopArray[i].bopname << endl;
        }
    }
}
void p6_4(void)
{
    const struct bop bopArray[5] = {                             //给结构体变量初始化的方式
        {"Wimp Macho", "YYY", "Y----", 0},
        {"XXXXXXXX", "2XXXX", "3XXXXX", 1},
        {"AAAAAAAA", "2AAAA", "3AAAAA", 2},
        {"BBBBBBBB", "2BBBB", "3BBBBB", 0},
        {"CCCCCCCC", "4CCCC", "3CCCCC", 1}
    };
    char choice = 0;

    cout << "Benevolent Order of Proframers Report" << endl;
    cout << left << setw(30) << "a. display by name" << "b. display by title" << endl;
    cout << left << setw(30) << "c. display by bopname" << "d. display by preference" << endl;
    cout << left << setw(30) << "q. quit" << endl;
    cout << "Enter your choice:";

    while (cin >> choice)
    {
        if (choice == 'q')
        {
            break;
        }
        switch (choice)
        {
        case 'a':
            display_by_name(bopArray, 5);
            break;

        case 'b':
            display_by_title(bopArray, 5);
            break;

        case 'c':
            display_by_bopname(bopArray, 5);
            break;

        case 'd':
            display_by_preference(bopArray, 5);
            break;

        default:
            break;
        }
        cout << "Next choice:";
    }
    cout << "Bye!" << endl;
    return;
}