How to copy contents in an array of object into another array in C++?

Question

#include "stdafx.h"
#include<iostream>
using namespace std;
class bank
{
public: char name[20];
public: float balance;
public: void get()
{
    cout << "\nEnter name and balance in Account respectively\n";
    cin >> name >> balance;
}
public: void display()
{
    cout << "Name: " << name << "    Balance: " << balance;
}
};
void main()
{
    int i = 0;
    bank b[10];
    bank max;
    bank temp;
    for (i = 0; i < 10; i++)
    {
        b[i].get();
    }
    for (i = 0; i < 10; i++)
    {
        if (b[i + 1].balance > b[i].balance)
        {
            max.balance = b[i + 1].balance;
            max.name = b[i + 1].name;//Error 1 error C2106: '=' : left operand must be l-value
        }
        else
        {
            temp.balance = b[i + 1].balance;
            temp.name = b[i + 1].name;//Error 2 error C2106: '=' : left operand must be l-value
            b[i + 1].balance = b[i].balance;
            b[i + 1].name = b[i].name;//Error 3 error C2106: '=' : left operand must be l-value
            b[i].balance = temp.balance;
            b[i].name = temp.name;//Error 4 error C2106: '=' : left operand must be l-value
            max.balance = b[i + 1].balance;
            max.name = b[i + 1].name;//Error 5  error C2106: '=' : left operand must be l-value
        }

    }
    max.display();
}

In this program I've to take input as name and balance of 10 people and display the output as name and balance corresponding to the highest balance. Besides the errors shown in the code itself as comments, I'm also getting another code at same those lines only where I've put a comment regarding the error. That other error is:

IntelliSense: expression must be a modifiable lvalue

I'm using Visual Studio Professional 2013 and the code is in visual C++

And while you're at it, use `std::vector b(10)` instead of `bank b[10]`. — TartanLlama, Sep 12 '14 at 14:18
Look at [`std::copy`](http://en.cppreference.com/w/cpp/algorithm/copy) while you're at it. — Captain Obvlious, Sep 12 '14 at 14:23
Isn't there also an error in the way you access the `bank b[10]` value in the `for` loop? If you're looping from 0 to 10, and ask for `b[i+1]` when `i` is 9.. you're going out of bounds, no? — Alejandro, Sep 12 '14 at 14:24
Generally in C++, one would not repeat the `public:` for each declaration, but have it generally once (since everything that follows is then public until the next `private:` or `protected:`) — crashmstr, Sep 12 '14 at 14:28
I put #include on the top and replaced char[20] with std::string and it worked. Thanks — Abhishek, Sep 12 '14 at 14:31

score 1 · Accepted Answer · edited May 23 '17 at 11:57

You cannot assign char[] variable to another char[] variable. You should use strcpy function to do that (and dont forget to include<cstring> first). See this how to copy char array to another char array in C? for further explanation.

if it changes like this, It should be ok:

#include<iostream>
#include<cstring>
using namespace std;
class bank
{
    public: char name[20];
    public: float balance;
    public: void get()
    {
        cout << "\nEnter name and balance in Account respectively\n";
        cin >> name >> balance;
    }
    public: void display()
    {
        cout << "Name: " << name << "    Balance: " << balance;
    }
};
void main()
{
    int i = 0;
    bank b[10];
    bank max;
    bank temp;
    char tempstr[20]; // use this for temporary string
    for (i = 0; i < 3; i++)
    {
        b[i].get();
    }
    for (i = 0; i < 2; i++) // you should change the upper bound to 9
                            // so it not crash when i = 9
    {
        if (b[i + 1].balance > b[i].balance)
        {
            max.balance = b[i + 1].balance;
            strcpy(max.name, b[i+1].name); // use strcpy
        }
        else
        {
            temp.balance = b[i + 1].balance;
            strcpy(temp.name, b[i+1].name); // use strcpy
            b[i + 1].balance = b[i].balance;
            strcpy(b[i+1].name, b[i].name); // use strcpy
            b[i].balance = temp.balance;
            strcpy(b[i].name, temp.name); // use strcpy
            max.balance = b[i + 1].balance;
            strcpy(max.name, b[i+1].name); // use strcpy
        }

    }
    max.display();
}

How to copy contents in an array of object into another array in C++?

1 Answers1