在 C++ 中创建一个类对象数组

create an array of class objects in c++

提问by Frustrated Coder

Hi guys I want to make an array of class objects....so that I can keep on creating as many objects during runtime as and when required I wrote the following code, but its giving me error:

嗨，伙计们，我想创建一个类对象数组....这样我就可以在运行时根据需要继续创建尽可能多的对象，我编写了以下代码，但它给了我错误：

class contact{
public:
    string name;//ALL CLASS VARIABLES ARE PUBLIC
    int phonenumber;
    string address;

    contact(){//Constructor
        name= NULL;
        phonenumber= NULL;
        address= NULL;
    }

    void input_contact_name(string s){//function to take contact name
        name=s;
    }
    void input_contact_number(int x){//function to take contact number
        phonenumber=x;
    }
    void input_contact_address(string add){//function to take contact address
        address=add;
    }
}

int main(){
    contact *d;
    d= new contact[200];
    string name,add;
    int choice;//Variable for switch statement
    int phno;
    static int i=0;//i is declared as a static int variable
    bool flag=false;
    cout<<"\tWelcome to the phone Directory\n";//Welcome Message
    cout<<"Select :\n1.Add New Contact\n2.Update Existing Contact\n3.Delete an Existing Entry\n4.Display All Contacts\n5.Search for a contact\n6.Exit PhoneBook\n\n\n";//Display all options
    cin>>choice;//Input Choice from user
    while(!flag){//While Loop Starts
        switch(choice){//Switch Loop Starts
        case 1:
            cout<<"\nEnter The Name\n";
            cin>>name;
            d[i]->name=name;
            cout<<"\nEnter the Phone Number\n";
            cin>>phno;
            d[i]->input_contact_number(phno);
            cout<<"\nEnter the address\n";
            cin>>add;
            d[i]->input_contact_address(add);
            i++;
            flag=true;
        }
    }
    return 0;
}

Please can some one out figure out the reason?? Thanks in advance

请问有大佬能查一下原因吗？？提前致谢

回答by ildjarn

Manyproblems:

很多问题：

1. Missing semicolon on the closing brace of the class, as maverik noted
2. Use of stringwithout using namespace std;or using std::string;(or #include <string>for that matter)
3. Ditto #2 for cinand cout(and <iostream>)
4. d[i]->is wrong; d[i]is a contact&, not a contact*, so use .instead of ->
5. name= NULL;and address= NULL;are nonsensical -- stringis not a pointer type, and already default-constructs to empty
6. phonenumber= NULL;is technicallyvalid, but still 'wrong'

1. 正如 maverik 指出的那样，类的右大括号上缺少分号
2. 使用string没有using namespace std;或using std::string;（或#include <string>就此而言）
3. 同上 #2cin和cout（和<iostream>）
4. d[i]->是错的; d[i]是 a contact&，不是 a contact*，所以用.代替->
5. name= NULL;并且address= NULL;是无意义的——string不是指针类型，并且已经默认构造为空
6. phonenumber= NULL;是技术上有效的，但仍然是“错误的”

Also, good lord, use some whitespace in your code.

另外，老天爷，在您的代码中使用一些空格。

EDIT(in response to comment): Your constructor should look like:

编辑（回应评论）：您的构造函数应如下所示：

contact() : phonenumber() { }

回答by maverik

You forget the ;

你忘记了 ;

class contact {
    ...
};  // <- ; is neccessary