c++ - C++中实现[]重载报错？

Question

在visual_studio中想做一个[]重载的小练习，

#include <cstring>#include <iostream>using namespace std;struct Person{    double salary;    char *name;};class SalaryManage{private:    Person *employ;    int max;    int n;public:    SalaryManage(int Max = 0)        :max(Max),n(0),employ(new Person[max])    {    }    double  &operator[](char *Name)     {        Person *p;        for (p = employ;p < employ + n;p++)            if (strcmp(p->name, Name) == 0)                return p->salary;        p = employ + n++;        p->name = new char[strlen(Name) + 1];        strcpy(p->name, Name);        p->salary = 0;        return p->salary;    }    void display()    {        for (int i = 0;i < n;i++)            cout << employ[i].name << "  " << employ[i].salary << endl;    }    ~SalaryManage()    {        delete[] employ;    }};int main(){    SalaryManage s(3);    s["张三"]  = 2188.88;    s["里斯"] = 1234.65;    s["王五"] = 3200.98;    cout << "张三\t" << s["张三"] << endl;    cout << "里斯\t" << s["里斯"] << endl;    cout << "王五\t" << s["王五"] << endl;    s.display();}

可是主函数部分显示

作为C++新手，请大佬们帮忙指点一二

Answer 1

这个错误是由于您在 SalaryManage 类的 operator[] 中没有正确地处理数组越界的情况。当您没有找到与 Name 匹配的名称时，您创建了一个新的 Person 对象并将其添加到数组的末尾，但您没有更新 n 的值，这导致在尝试访问不存在的数组索引时出现错误。

为了解决这个问题，您应该在添加新 Person 对象后将 n 的值增加 1。这样，您就可以正确地访问新添加的元素。此外，您应该在 display 函数中更新数组的长度。以下是更正后的代码：

#include <cstring>#include <iostream>using namespace std;struct Person{ double salary; char *name;};class SalaryManage{private: Person *employ; int max; int n;public: SalaryManage(int Max = 0) :max(Max),n(0),employ(new Person[max]) { } double& operator[](const char* Name)  { Person *p = nullptr; for (int i = 0; i < n; i++) { if (strcmp(employ[i].name, Name) == 0) { p = &employ[i]; break; } } if (p == nullptr) { p = &employ[n++]; p->name = new char[strlen(Name) + 1]; strcpy(p->name, Name); p->salary = 0; } return p->salary; } void display() const { for (int i = 0; i < n; i++) cout << employ[i].name << "  " << employ[i].salary << endl; } ~SalaryManage() { delete[] employ; }};int main(){ SalaryManage s(3); s["张三"]  = 2188.88; s["里斯"] = 1234.65; s["王五"] = 3200.98; cout << "张三\t" << s["张三"] << endl; cout << "里斯\t" << s["里斯"] << endl; cout << "王五\t" << s["王五"] << endl; s.display();}