Open file by its full path in C++

Question

Hello,

I want the user to give me the full path where the file exists and not just the file name. How do I open the file this way?

Is it something like this:

ifstream file;
file.open("C:/Demo.txt", ios::in);

Because it doesnt seem to work..I think..

Thanks in advance,

Greg

Answer 1

You can use a full path with the fstream classes. The folowing code attempts to open the file demo.txt in the root of the C: drive. Note that as this is an input operation, the file must already exist.

#include <fstream>
#include <iostream>
using namespace std;

int main() {
   ifstream ifs( "c:/demo.txt" );       // note no mode needed
   if ( ! ifs.is_open() ) {                 
      cout <<" Failed to open" << endl;
   }
   else {
      cout <<"Opened OK" << endl;
   }
}

What does this code produce on your system?

Answer 2

Normally one uses the backslash character as the path separator in Windows. So:

ifstream file;
file.open("C:\\Demo.txt", ios::in);

Keep in mind that when written in C++ source code, you must use the double backslash because the backslash character itself means something special inside double quoted strings. So the above refers to the file C:\Demo.txt.

Answer 3

The code you presented is not enough to tell what the problem may be.
Why do you think that it does not work?
If it really does not work check if the file exists and that you have the access rights to the file.