c++ - 用户定义的函数仅返回可能值中的 1 个

Question

1. I am attempting to write a program that calls functions to perform each task specified in my assignment. Everything seems to be working properly, except when i choose which form to use (the first step) it chooses choice 2, whether i choose 1 or 2. Please Help!

// Translates Linear equations from Point-Slope Form to Two-Point Form and Vice Versa
// Also takes given information and displays Slope-Intercept Form

#include <iostream>
#include <cmath>

using namespace std;

int getProblem();
double get2Pt(double& x1, double& y1, double& x2, double& y2);
double getPtSlope(double& x1, double& y1);
double slopeIntcptFrom2Pt(double& x1, double& y1, double& x2, double& y2);
double intcptFromPtSlope(double slope, double& x1, double& y1);
void display2Pt(double x1, double y1, double x2, double y2);
void displayPtSlope(double slope, double x1, double y1);
void displaySlopeIntrcpt(double slope, double  yIntrcpt);

int main()
{
    double x1, x2, y1, y2, slope, yIntcpt;
    int choice;

    choice = getProblem();

    if (choice = 1)
    {   slope = get2Pt(x1, y1, x2, y2);
        yIntcpt = slopeIntcptFrom2Pt(x1, y1, x2, y2);
        display2Pt(x1, y1, x2, y2);
        displaySlopeIntrcpt(slope, yIntcpt);
    }
    else if(choice = 2)
    {
        slope = getPtSlope(x1, y1);
        yIntcpt = intcptFromPtSlope(slope, x1, y1);
        displayPtSlope(slope, x1, y1);
        displaySlopeIntrcpt(slope, yIntcpt);
    }
return 0;
}

int getProblem()
{
    int choice;
    cout << "Select the form you would like to convert to Slope-Intercept Form:" << endl
         << "1) Two-Point From (2 Points on the line are known)" << endl << "2) Point-Slope Form (The slope and one point on the line are known)" << endl;
    cin >> choice;
    return choice;
}
double getPtSlope(double& x1, double& y1)
{
    double slope;
    cout << "Enter the Slope =>" << endl;
    cin >> slope;
    cout << "Enter the X/Y Coordinates of the point, separated by a space =>" << endl;
    cin >> x1 >> y1;
    return slope;
}
double get2Pt(double& x1, double& y1, double& x2, double& y2)
{
    double slope;

    cout << "Enter the X/Y Coordinates of the First point, separated by a space =>" << endl;
    cin >> x1 >> y1;
    cout << "Enter the X/Y Coordinates of the Second point, separated by a space =>" << endl;
    cin >> x2 >> y2;

    slope = ((y2 - y1) / (x2 - x1));
    return slope;
}
double slopeIntcptFrom2Pt(double& x1, double& y1, double& x2, double& y2)
{
    double slope, yIntcpt;
    slope = ((y2 - y1) / (x2 - x1));
    yIntcpt = (slope * x1) + y1;
    return yIntcpt;
}
double intcptFromPtSlope(double slope, double& x1, double& y1)
{
    double yIntcpt;
    yIntcpt = (slope * x1) + y1;
    return yIntcpt;
}
void displayPtSlope(double slope, double x1, double y1)
{
    if (y1 >= 0)
    {
        if (x1 >= 0) cout << "y - " << y1 << " = " << slope << "(x - " << x1 << ")" << endl << endl;
        else cout << "y - " << y1 << " = " << slope << "(x + " << fabs(x1) << ")" << endl << endl;
    }
    else
    {
        if (x1 >= 0) cout << "y + " << fabs(y1) << " = " << slope << "(x - " << x1 << ")" << endl << endl;
        else cout << "y + " << fabs(y1) << " = " << slope << "(x + " << fabs(x1) << ")" << endl << endl;
    }
    return;
}
void display2Pt(double x1, double y1, double x2, double y2)
{
    cout << "   " << y2 << " - " << y1 << endl << "m = ----------------------" << endl
         << "   " << x2 << " - " << x2 << endl << endl;
}
void displaySlopeIntrcpt(double slope, double  yIntrcpt)
{
    if (yIntrcpt >= 0) cout << "y = " << slope << "x + " << yIntrcpt;
    else cout << "y = " << slope << "x " << yIntrcpt;
    return;
}

Answer 1

您正在将 1 分配给 choice 而不是比较是否相等:

if (choice = 1)

改成这个

if (choice == 1)
...
else if(choice == 2)