Multiple Constructors

[Sastraxi]

Okay, I've run into some problems
Dug out my old math texts to do this... oddly enough though I've remembered them all...

// Lines.cpp
#include <iostream>
using namespace std;

class nline {
    double l_m;
    double l_b;
public:
    nline(double x1, double y1, double x2, double y2); // 2x Points
    nline(double x, double y, double m); // Point/Slope
    nline(double m, double b); // y = mx + b
    nline(int a, int b, int c); // Ax + By + C = 0
    ~nline();
    double slope();
    double yint();
};

nline::nline(double x1, double y1, double x2, double y2) {
    l_m = (y2 - y1) / (x2 - x1);
    l_b = y1 - (x1 * l_m);
}

nline::nline(double x, double y, double m); {
    l_m = m;
    l_b = y - (x * l_m);
}

nline::nline(double m, double b) {
    l_m = m;
    l_b = b;
}

nline::nline(int a, int b, int c) {
    l_m = -a / b;
    l_b = c / b;
}

nline::~nline() {
    l_m = 0;
    l_b = 0;
}

double nline::slope() {
    return l_m;
}

double nline::yint() {
    return l_b;
}


int main() {
nline line1(8, -2, 5, 7);
    cout << line1.slope << endl;
    cout << line1.yint << endl;
    return 0;
}
// EOF 

And it spits out like 51 erros. What's wrong? Do classes have to be in header files or something?