To read from a file, create an ifstream object and pass the filename to its constructor: ifstream file("data.txt"); This attempts to open the file immediately. You can also declare first and open later: ifstream file; file.open("data.txt"); Both approaches work the same way.
The file is ready for reading after successful opening. Always check if opening succeeded before reading. A file might not exist or you might lack permissions. you'll cover error checking in a later unit.