Simple .txt File-Reading with ifstream

Question

Just what is probably a basic question for something I haven't been able to figure out all day. Here's a snippet of code in C++:

Escape::Escape(std::string filename)
{
   std::ifstream file;
   file.open(filename.c_str());
   if (file.is_open()) {
      file >> gridWidth >> gridHeight >> nKeys;
      std::cout << "gridWidth = " << gridWidth << std::endl;
      std::cout << "gridHeight = " << gridHeight << std::endl;
      std::cout << "nKeys = " << nKeys << std::endl;
      /* irrelevant code below */

Basically I want this code to read the first three integers of a text file and save them into the variables gridWidth, gridHeight, and nKeys. These are private integers of a class called "Escape". Here are the first few lines of the text file:

8
8
1
BUL--/EUR--/BUL--/BU---/BU---/BU---/BU---/BUR--/
(more text below)

And here is some sample output of this code:

gridWidth = 107764358
gridHeight = -991553646
nKeys = 0

On running this code multiple times, gridWidth and gridHeight are always junk and nKeys is always 0. Any ideas as to what I am doing wrong?

EDIT: The problem was with the filename I passed to file.open() . I passed in the relative filename which, although openable, was not linkable to the ifstream. The problem was resolved by using the text file's absolute filename instead.

Answer 1

Instead of file >> gridWidth >> gridHeight >> nKeys; do this instead:

while(file >> gridWidth && file >> gridHeight && file >> nKeys)

This would be better than storing the results in a string and then having to do a conversion.