Thread: Newbie programmer, few quick questions...

  1. #1
    Registered User
    Join Date
    Oct 2005

    Newbie programmer, few quick questions...

    I have just started learning C/C++. As practice i started doing a few challenge exercises. I am working on one such exercise in which i must write a program which can decide if three given points form an isosceles triangle (triangle with at least 2 congruent sides, for math illiterates). This is done by first making sure the points are not collinear (form a straight line) and then checking if the distance between any two points is the same. But i get a couple strange errors when compiling. I'm pretty sure the math is right. Anyway here is the code (d12 is distance between point 1 and 2, d13 = distance between point 1 and 3, you get it.):

    #include <iostream>
    using namespace std;
    int main()
        int x1, y1, x2, y2, x3, y3, d12, d23, d13;
        bool is_collinear;
        is_collinear = 0;
        cout << "Enter x1";
        cin >> x1;
        cout << "Enter y1";
        cin >> y1;
        cout << "Enter x2";
        cin >> x2;
        cout << "Enter y2";
        cin >> y2;
        cout << "Enter x3";
        cin >> x3;
        cout << "Enter y3";
        cin >> y3;
        d12 = (((x1 - x2)^2) + ((y1 - y2)^2));
        d13 = (((x1 - x3)^2) + ((y1 - y3)^2));
        d23 = (((x2 - x3)^2) + ((y2 - y3)^2));
        if  ((y2 - y1) * (x3 - x1)) == ((y3 - y1) * (x2 - x1))
            is_collinear = 1;
        if ((is_collinear == 0) && ((d12 == d23) || (d12 == d13) || (d23 == d13)))
            cout << "It is an isosceles triangle!";
            cout << "It's not an isosceles triangle.";
    when attempting to compile i get the following errors. Syntax error before '==' token on line 30 (first IF statement) and syntax error before '.' token on cin.get() function at global scope. I have no idea whats wrong. I have torn through many tutorials and as far as i can see there is nothing wrong with the code. What is wrong? BTW, i am using DevC++ 5. Thanx!

  2. #2
    Devil's Advocate SlyMaelstrom's Avatar
    Join Date
    May 2004
    Out of scope
    Try this:
    if  ((y2 - y1) * (x3 - x1) == (y3 - y1) * (x2 - x1))
    You had too many parenthesis.
    Sent from my iPadŽ

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