C语言平面几何5-两点确定一条直线

/* 两个不同点A,B确定一条直线，AB相同返回的值全0 *  直线方程：Ax+By+c=0 *  A = y2 - y1; *  B = x1 - x2; *  C = -A*x1 - B*y1 = x2*y1 - x1*y2; */Line LineMake(Point A, Point B){Line l;l.A = B.y - A.y;l.B = A.x - B.x;l.C = B.x * A.y - A.x * B.y;return l;}