c++通讯录所遇见的问题

问题遇到的现象和发生背景

通讯录项目
问题出在170modifyPerson

在项目运行时，如果在运行之初选择5，修改联系人，则会出现查无此人。但在储存了一个联系人之后再修改联系人，无论输入的联系人是否存在都会进入编辑模块而无法出现查无此人

用代码块功能插入代码，请勿粘贴截图
#include 
#include 
#define Max 100
using namespace std;

void showMenu()
{
    cout << "1,添加联系人" << endl;
    cout << "2,显示联系人" << endl;
    cout << "3,删除联系人" << endl;
    cout << "4,查找联系人" << endl;
    cout << "5,修改联系人" << endl;
    cout << "6,清空联系人" << endl;
    cout << "0,退出通讯录" << endl;
}

struct Person
{
    string m_Name;
    int m_Sex;
    int m_Age;
    string m_phone;
    string m_Addr;
};

struct Addressbooks//定义通讯录结构体
{
    struct Person personArray[Max];//通讯录中保存的联系人数组，personArray是数组名

    int m_Size;
};


void addPerson(Addressbooks* abs)//添加联系人
{
    if (abs->m_Size == Max)//判断通讯录是否已满，若满了就不再添加  
    {
        cout << "通讯录已满" << endl;
        return;
    }
     else
    {
        string name;
        cout << "请输入姓名" << endl;
        cin >> name;
        abs->personArray[abs->m_Size].m_Name = name;//abs通讯录中有个名为personArray的数组[第几个元素]的名字

          cout << "请输入性别：" << endl;
        cout << "1-----男" << endl;
        cout << "2-----女" << endl;
        int sex = 0;

        while (true)
        {
            cin>>sex;
            if (sex == 1 || sex == 2)
            {
                abs->personArray[abs->m_Size].m_Sex = sex;
                break;
            }
            cout << "请重新输入" << endl;
        }
        cout << "请输入年龄" << endl;
        int age = 0;
        cin >> age;
        abs->personArray[abs->m_Size].m_Age = age;

        cout << "请输入联系电话" << endl;
        string phone;
        cin >> phone;
        abs->personArray[abs->m_Size].m_phone = phone;

        cout << "请输入地址" << endl;
        string address;
        cin >> address;
        abs->personArray[abs->m_Size].m_Addr = address;

        abs->m_Size++;
        cout << "添加成功" << endl;

        system("pause");//按任意键继续
        system("cls");//清屏操作

    }
}

void showPeson(Addressbooks* abs)
{
    if (abs->m_Size == 0)
    {
        cout << "当前无联系人" << endl;
    }
    else
    {
        for (int i = 0; i < abs->m_Size; i++)
        {
            cout << "姓名 ：" << abs->personArray[i].m_Name << "\t";
            cout << "性别 ：" << (abs->personArray[i].m_Sex == 1 ? "男" : "女") << "\t";
            cout << "年龄 ：" << abs->personArray[i].m_Age << "\t";
            cout << "电话 ：" << abs->personArray[i].m_phone << "\t";
            cout << "住址 ：" << abs->personArray[i].m_Addr << endl;
        }
    }
    system("pause");
    system("cls");
}

int isExist(Addressbooks* abs,string name)//参数1：通讯录；参数2：对比姓名
{
    for (int i = 0; i < abs->m_Size; i++)
    {

        return i;//找到了，返回这个人在数组中的下表编号
    }
    return -1;//如果遍历结束都没有找到，返回-1
}

void deletePerson(Addressbooks* abs)
{
    cout << "请输入将要删除的联系人" << endl;

    string name;
    cin >> name;
    //ret== -1 未查到；ret != -1 查到了
    int ret = isExist(abs, name);

    if (ret == -1)
    {
        cout << "未查询到该联系人" << endl;
    }
    else
    {
        for (int i = ret; i < abs->m_Size; i++)
        {
            abs->personArray[i] = abs->personArray[i + 1];
        }
        abs->m_Size--;
        cout << "删除成功" << endl;
//要删除某人，将此人后面的数据向前移动，并且让通讯录中记录的人员个数做-1操作
    }

    system("pause");
    system("cls");
}

void findPerson(Addressbooks* abs)
{
    string name;
    cout << "请输入要查找的联系人" << endl;
    cin >> name;

    int ret = isExist(abs, name);
    if (ret != -1)
    {
        cout << "姓名 ：" << abs->personArray[ret].m_Name << "\t";
        cout << "性别 ：" << (abs->personArray[ret].m_Sex == 1 ? "男" : "女") << "\t";
        cout << "年龄 ：" << abs->personArray[ret].m_Age << "\t";
        cout << "电话 ：" << abs->personArray[ret].m_phone << "\t";
        cout << "住址 ：" << abs->personArray[ret].m_Addr << endl;
    }
    else
    {
        cout << "查无此人" << endl;
    }

    system("pause");
    system("cls");
}

void modifyPerson(Addressbooks* abs)
{
    cout << "请输出要修改的人名" << endl;
    string name;

    cin >> name;

    int ret = isExist(abs, name);
    if (ret != -1)
    {
        int n = 0;
        cout << "请问要修改哪一部分" << endl
            << "1----姓名" << endl
            << "2----性别" << endl
            << "3----年龄" << endl
            << "4----电话" << endl
            << "5----住址" << endl
            << "0----退出" << endl;
        cin >> n;
            switch (n)
            {
            case 1:
            {
                string name;
                cout << "请输入修改后的姓名" << endl;
                cin >> name;
                abs->personArray[ret].m_Name = name;
                break;
            }
            case 2:
            {
                int sex;
                cout << "请输入修改后的性别" << endl
                    << "1----男" << endl
                    << "2----女" << endl;
                cin >> sex;
                abs->personArray[ret].m_Sex = sex;
                break;
            }
            case 3:
            {
                int age;
                cout << "请输入修改后的年龄" << endl;
                cin >> age;
                abs->personArray[ret].m_Age = age;
                break;
            }
            case 4:
            {
                string num;
                cout << "请输入修改后的电话号码" << endl;
                cin >> num;
                abs->personArray[ret].m_phone = num;
                break;
            }
            case 5:
            {
                string addr;
                cout << "请输入修改后的地址" << endl;
                cin >> addr;
                abs->personArray[ret].m_Addr = addr;
                break;
            }
            case 0:
            {
                break;
            }
            default:
                break;
            }
            
    }
    else
    {
        cout << "查无此人" << endl;
    }

    system("pause");
            system("cls");

}

int main()
{
    Addressbooks abs;
    abs.m_Size = 0;
    int select = 0;//创建用户选择输入的变量；

    while (true)
    {

        showMenu();

        cin >> select;

        switch (select)
        {
        case 1:
            addPerson(&abs);
            break;
        case 2:
            showPeson(&abs);
            break;
        case 3://case 后如果是很长一串代码，则需要用{}将其括起来
            deletePerson(&abs);
            break;
        case 4:
            findPerson(&abs);
            break;
        case 5:
            modifyPerson(&abs);
            break;
        case 6:
            break;
        case 0:
            cout << "欢迎下次使用" << endl;
            system("pause");
            return 0;
            break;
        default:
            break;
        }
    }



    system("pause");
    return 0;
}