How to use IStringStream to read from a file?

Question

I need to read in an expression from a file using a string stream and convert the expression to into another form. But I am having trouble figuring out how to read lines from the file using the Istringstream. Can anyone help me with the #includes and syntax for this? Thanks

Answer 1

#include <fstream>

std::ifstream file("filename.txt");

StuffType stuff;
while(file >> stuff)
{
    // If you are here you have successfully read stuff.
}

Answer 2

As an addition to the answer of Dave above: to read one line from a file, you can use the following code:

char buf[256];
file.getline(buf,256);

The character string buf then contains the line of text in the file.