How do I use fstream functions in a class?

[raheelX]

okay so i want to design a class that will open a text file and manipulate the data in it. and i have to use all these functions from fstream like ifstream, ofstream, seekg etc. the problem is that i can't get the first part to work (getting my constructor to open the file using ifstream). I've posted my test.h file below.

#ifndef TEST_H_INCLUDED
#define TEST_H_INCLUDED
#include <iostream>
#include <fstream>
#include <string>
 
using namespace std;
using std::ifstream;
 
class Test
{
private:
    float hour, minute, second, vrms, irms, time;
    string fileName;
public:
    Test(string);
};
 
Test::Test(string name)
{
    fileName = name;
    ifstream dataFile(fileName);
}
 
#endif // TEST_H_INCLUDED

any help will be appreciated.

[divideby0]

fileName is a std::string, but fstream objects want a const char * as the first argument; use fileName.c_str() or maybe fileName.data()

[weaknessforcats]

Your ifstream object datafile is a local variable in your constructor. It's deleted when the constructor completes.

This variable should be a private member variable so it can be used by other member functions.