how to get proper inputs

i have lately been running into lots of problems where i have a "string" and the items needs a "char" or vise versa, i have been trying to stay to "strings". I also think it has to do with the calls im using are old calls using the "char".
any help on how to open the file correctly with what i am using or if im using the wrong call to open the file a replacement

Code:

---

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
        string fileName;
        cout << "Please enter file to open:";
        cin >> fileName;

        ifstream fin;
        string szLine = "";
        fin.open(fileName);                        // this is where my problem stems from
        if (fin.fail())
        {       
                cout << " could not find filename\n";
                return -1;
        }
        while (getline(fin, szLine))
                cout << szLine;
       
        fin.close();
       

        system("pause");
        return 0;
}

---

You can always use fileName.c_str(). It will return a const char*, I believe.