Question

I’m tinkering with a projecteuler problem and I encountered the following really odd behaviour. And I can’t for the life of me figure out whats going on.

As the screenshot shows. The condition evaluates to false, and the if-statment executed as if it was true.

I feel like I’m going crazy here.

Updated code: http://ideone.com/L7KMu

Edit: The actual values for next.x and next.y just prior to the condition are
0.324583, 9.97891

The are unchanged after the if statement.

Answer 1

Having compiled the code, it appears that the abs you are calling is not std::abs, overloaded for floating point, but integer abs. Try this amendment to the code:

// get the root not relating to this point
nextX = (abs(solved.first - next.x) < EPSILON) ? solved.second : solved.first;
nextY = k * nextX + m;
prev = next;
next = point(nextX, nextY);

cout << abs(next.x) << ", " << std::abs(next.x) << endl;
if ( std::abs(next.x) < 0.01){
    cout << "Here1" << endl;
    if ( next.y > 0){
        cout << "Here2" << endl;
        foundExit = true;
    }
}

You’ll notice that the cout line is printing different values for abs and std::abs.