inf 输出计算线斜率

Question

我是 C++ 的新手。

我在下面写了这段代码，它应该告诉我两条线是否有交点，所以我认为 y=Mx+B 方程中 "M" 相等的两条线不应该相交，所有其他的会。

程序似乎理解这一点，但除非输入线段的斜率是 0，否则它会输出 inf 或 -inf。

为什么会这样？

#include <iostream>
using namespace std;
int main ()
{
typedef double vector2d[2];
vector2d pointA, pointB, pointC, pointD;
double LineSeg1, LineSeg2;
double yes, no;


cout << "Enter x for point A: ";
cin >> pointA[0];
cout << "Enter y for point A: ";
cin >> pointA[1];
cout << "Point A = (" << pointA[0] << "," << pointA[1] << ")" << endl;

cout << "Enter x for point B: ";
cin >> pointB[0];
cout << "Enter y for point B: ";
cin >> pointB[1];
cout << "Point B = (" << pointB[0] << "," << pointB[1] << ")" << endl;

cout << "Enter x for point C: ";
cin >> pointC[0];
cout << "Enter y for point C: ";
cin >> pointC[1];
cout << "Point C = (" << pointC[0] << "," << pointC[1] << ")" << endl;

cout << "Enter x for point D: ";
cin >> pointD[0];
cout << "Enter y for point D: ";
cin >> pointD[1];
cout << "Point D = (" << pointD[0] << "," << pointD[1] << ")" << endl;

LineSeg1 = ((pointB[1]-pointA[1])/(pointB[0]-pointB[0]));
cout << "slope segment 1 = (" << LineSeg1 << endl;

LineSeg2 = ((pointD[1]-pointC[1])/(pointD[0]-pointC[0]));
cout << "slope segment 2 = (" << LineSeg2 << endl;


if ( LineSeg1 == LineSeg2 ) {
    cout << "no\n";
}

else ( LineSeg1 != LineSeg2 ) ;{
    cout << "yes\n";
}

return 0;

}

Answer 1

这一行：

LineSeg1 = ((pointB[1]-pointA[1])/(pointB[0]-pointB[0]));

除以零错误。

我认为等式应该是：

LineSeg1 = ((pointB[1]-pointA[1])/(pointB[0]-pointA[0]));

inf 输出计算线斜率

inf output computing line slopes

c++

line-intersection