read/write struct from text file in c++

Question

I have been stuck in the same place with this code for a while. And finally decided to ask it online. Any help would be appreciated.

I have created a struct and I'm able to add data to the struct but still not sure whether I'm following the correct methodology. The main problem lies when I try to read the data from the text file.

I seem to be getting an error saying :

error C2678: binary '>>' : no operator found which takes a left-hand operand of type 'std::ifstream' (or there is no acceptable conversion)

The Struct:

struct bankDetails              //structure for bank details
{
    int acc_number;
    double acc_balance;
    double deposit_amt;
    double withdraw_amt;
    double interest_rate;
    //char acc_type;


};


struct CustDetails                     //structure for account details
{
    string cust_name;
    string cust_pass;
    bankDetails bankAccounts[99];
};

This is the code I wrote to read from the file.

CustDetails loadDataFromFile ()
{
    CustDetails x;
    ifstream  dimensionsInfile; 
    dimensionsInfile.open ("storage.txt");
    for (int i=0; i < 2; i++)                                                               
    {   // write struct data from file  
        dimensionsInfile>>
        &x.bankAccounts[i].acc_balance>>
        &x.bankAccounts[i].acc_number>>
        &x.cust_nam>>
        &x.cust_pass>>
        &x.bankAccounts[i].withdraw_amt>>
        &x.bankAccounts[i].deposit_amt>>
        &x.bankAccounts[i].interest_rate>>
        cout<<"Data loaded"<<endl;
    } 
    return x;

}

The code to write into the file:

void details_save(int num,CustDetails x)
{

    string  filePath = "storage.txt";                                                                               
    ofstream  dimensionsOutfile;                                                                    

    dimensionsOutfile.open ("storage.txt");                                             
    if (!dimensionsOutfile)
        {
            cout<<"Cannot load file"<<endl;
            return ;
        }
    else
        {
            for (int i=0; i < num; i++)                                                             
                {   // write struct data from file  
                    dimensionsOutfile<<
                    &x.bankAccounts[i].acc_balance<<
                    &x.bankAccounts[i].acc_number<<
                    &x.cust_name<<
                    &x.cust_pass<<
                    &x.bankAccounts[i].withdraw_amt<<
                    &x.bankAccounts[i].deposit_amt<<
                    &x.bankAccounts[i].interest_rate<<
                    cout<<" Customer 1 stored"<<endl;
                }
            cout <<"All details have been successfully saved"<<endl;
            dimensionsOutfile.close();
        }

}

Part of the main function:

#include "stdafx.h"
#include <string>
#include <string.h>
#include <ctime>
#include <fstream>
#include <sstream>
#include <iostream>
#include <iomanip>

int main()

{
    int maxNum;
    CustDetails c;
    c = loadDataFromFile(); //loads data from the file

    {
            //This part adds and changes values
    }

    details_save(maxNum, c); //saves data back to the file
        return 0;
}

I'm a beginner in C++ any help would be much appreciated. Cheers!!

Answer 1

In loadDataFromFile() just before

cout<<"";

replace the '>>' with ';'.

We cannot use >> operator with cout.

Although there is a better and easier way to do what you are doing. fstream.h has functions to directly write and read objects of classes or structures.

Here's the syntax:

<stream name>.read((char*)<object name>,sizeof(<struct/class name>));

So your loadDataFromFile can be simplified as:

CustDetails loadDataFromFile ()
{
CustDetails x;
ifstream  dimensionsInfile; 
dimensionsInfile.open ("storage.txt");                                                              
     // write struct data from file  
     dimensionsInfile.read((char*) CustDetails, sizeof(x));   
     cout<<"Data loaded"<<endl;
     return x;
}

Similarly write definition of Write function. It will save you a lot of time and trouble.