How to open a variable filename with ifstream

[Some new cpp programmer]

In a new and supposedly improved version of a scheduler program I am working on, I have encountered a problem: I need to open a file specified by the user. How can I get ifstream to accept a string variable as a filename?

[Galik]

std::string file_name = "my_file_name.txt";

std::ifstream ifs(file_name.c_str());

[Some new cpp programmer]

That worked, thanks.

[Some new cpp programmer]

Mayby not, when I use "ifs" for the ifstream and "file_name" for the file name it works fine, but when I change them around it doesn't.

Example:

string month;
string data [31];

cout << "Please enter a month" << endl;
cin >> month;

ifstream input(month.c_str());
for (int i = 1; i < 31; i++)
{
getline(input, data[i]);
cout << i;
cout << data[i] << endl;
}

input.close ( );

What am I doing wrong?
Also, can you use this same code for ofstream, or does that require something compleatly diffrent?

[Galik]

That looks like it should work. As long as you only type in a one word name when it asks you for month. Can you explain what exactly is going wrong?

And yes, its the same for ofstream;

[Some new cpp programmer]

Found the problem: I'm an idiot.

forgot to include the fstream library.

Everything works fine now.