嘿所以我在完成C ++家庭作业方面遇到了麻烦，而且我花了很多时间来研究我的错误。作业要求您编写一个读入用户输入矩形的程序。程序将询问以rec＆＃34; name＆＃34;开头的矩形的名称。 （即矩形＆＃34; John＆＃34;将作为rec John输入），左下角的坐标，矩形的长度和矩形的高度。程序将把它放在一个列表中并继续要求更多的矩形，直到用户输入矩形的名称为＆＃34;停止。＆＃34;程序将返回每个矩形的输入信息，然后将矩形缩放3.它将返回缩放的矩形的新左下角坐标，中点，矩形区域，周长，身高和长度。
这是我到目前为止所做的事情。
#include <iostream>
#include <string>
#include <vector>
using namespace std;
class Point
{
private:
double px;
double py;
public:
void setX(const double x);
void setY(const double y);
double getX() const;
double getY() const;
};
class Rectangle
{
private:
string name;
Point blPoint;
double length, height;
public:
void setName(const string & inName);
void setBottomLeft(const double x, const double y);
void setDimensions(const double inLength, const double inHeight);
string getName() const;
Point getBottomLeft() const;
double getLength() const;
double getHeight() const;
double area() const;
double perimeter() const;
Point midPoint() const;
void scaleBy3();
void display() const;
};
void welcome();
bool read_rect (const string promptName, const string errInvalidName, const string errUsedName, string & inName, vector<Rectangle> & list);
void readXYcoord (const string promptPointxy, double & xcord, double & ycord);
void readLH (const string promptLH, double & inLength, double & inHeight);
void addRect (const string Name, double x, double y, double inLength, double inHeight, vector<Rectangle> & list);
void dis_rec(vector<Rectangle> & list);
int main()
{
Rectangle rec;
vector<Rectangle>list;
string prompt1stName = "Enter the name of the first rectangle: ";
string promptName = "Enter the name of the next rectangle: ";
string errInvalidName = "Invalid input. Type 'rec' following by the name or 'stop' if done.";
string errUsedName = "This name is already being used!";
string inName;
string Name;
double x,y,length,height;
welcome ();
bool read = read_rect (prompt1stName, errInvalidName, errUsedName, inName, list);
while (read == false)
{
cout << "Try again! ";
read = read_rect (prompt1stName, errInvalidName, errUsedName, inName, list);
}
if (inName != "stop")
{
int a = inName.length() - 4;
Name = inName.substr(4,a);
double x, y;
string promptPointxy = "Enter " + Name + "'s bottom left x and y coords: ";
readXYcoord (promptPointxy, x, y);
double length, height;
string promptLH= "Enter " + Name + "'s length and height: ";
readLH (promptLH, length, height);
addRect(Name, x, y, length, height, list);
}
while (inName !="stop")
{
cout << "Thank you! ";
bool read = read_rect(promptName, errInvalidName, errUsedName, inName, list);
while (read == false)
{
cout << "Try again! " <<endl;
read = read_rect(promptName, errInvalidName, errUsedName, inName, list);
}
if (inName != "stop")
{
int a = inName.length() - 4;
Name = inName.substr(4, a);
double x, y;
string promptPoint = "Enter " + Name + "'s bottom left x and y coords: ";
readXYcoord(promptPoint, x, y);
double inLength, inHeight;
string promptLength = "Enter " + Name + "'s length and height: ";
readLH(promptLength, inLength, inHeight);
addRect(Name, x, y, inLength, inHeight, list);
}
}
if (list.size() != 0)
{
dis_rec(list);
}
else
{
cout << "You have no rectangles in your list." << endl;
}
return 0;
}
void welcome()
{
cout << "Welcome! Create your own list of rectangles." << endl;
cout << "You will be asked to provide information about each rectangle in your list by name." << endl;
cout << "Type the word 'stop' for the rectangle name when you are done." << endl;
cout << endl;
}
bool read_rect (const string promptName, const string errInvalidName, const string errUsedName, string & inName, vector<Rectangle> & list)
{
cout << promptName;
getline(cin, inName);
if (inName == "stop")
{
return (true);
}
else if (inName.substr(0,4) != "rec ")
{
cout<< errInvalidName <<endl;
return (false);
}
else
{
int j = 0;
for (int i = 0; i < list.size(); i++)
{
if (inName == "rec " + list[i].getName())
{
j = j+1;
}
}
if (j == 0)
{
return(true);
}
if (j != 0)
{
cout << errUsedName;
return(false);
}
}
}
void readXYcoord (const string promptPointxy, double & xcord, double & ycord)
{
cout << promptPointxy;
cin >> xcord;
cin >> ycord;
}
void readLH (const string promptLH, double & inLength, double & inHeight)
{
cout<< promptLH;
cin >> inLength;
cin >> inHeight;
cout << endl;
while (inLength <= 0 || inHeight <= 0)
{
cout << "Make length and height positive values. Try again.";
cout << promptLH;
cin >> inLength;
cin >> inHeight;
cout << endl;
}
}
void addRect (const string Name, double x, double y, double inLength, double inHeight, vector<Rectangle> & list)
{
Rectangle rec;
rec.setName(Name);
rec.setBottomLeft(x, y);
rec.setDimensions(inLength, inHeight);
list.push_back(rec);
}
void dis_rec(vector<Rectangle> & list)
{
cout<<"You have "<<list.size()<<" rectangle(s) in your list: "<<endl;
for(int i=0; i<list.size(); i++)
{
cout<<"Rectangle '"<<list[i].getName()<<"': ";
list[i].display();
cout<<"After scale by 3:";
list[i].scaleBy3();
list[i].display();
}
}
void Point::setX(const double x)
{
px = x;
}
void Point::setY(const double y)
{
py = y;
}
double Point::getX() const
{
return (px);
}
double Point::getY() const
{
return (py);
}
void Rectangle::setName(const string & inName)
{
name = inName;
}
void Rectangle::setBottomLeft(const double x, const double y)
{
blPoint.setX(x);
blPoint.setY(y);
}
void Rectangle::setDimensions(const double inLength, const double inHeight)
{
length = inLength;
height = inHeight;
}
string Rectangle::getName() const
{
return (name);
}
Point Rectangle::getBottomLeft() const
{
return (blPoint);
}
double Rectangle::getLength() const
{
return (length);
}
double Rectangle::getHeight() const
{
return (height);
}
double Rectangle::area() const
{
return(length*height);
}
double Rectangle::perimeter() const
{
return ( (height*3)+(length*3));
}
Point Rectangle::midPoint() const
{
Point midPoint;
double mpx = blPoint.getX() + 0.5 * length;
double mpy = blPoint.getY() + 0.5 * height;
midPoint.setX(mpx);
midPoint.setY(mpy);
return(midPoint);
}
void Rectangle::scaleBy3()
{
double mx = blPoint.getX() + 0.5 * length;
double my = blPoint.getY() + 0.5 * height;
double newmdx = mx - length;
double newmdy = my - height;
length= 3* length;
height = 3* height;
blPoint.setX(newmdx);
blPoint.setY(newmdy);
}
void Rectangle::display() const
{
cout << " Location is (" << blPoint.getX() << ", " << blPoint.getY() << "), length is " << length << ", height is " << height << "; Area is " << area() << "; perimeter is " << perimeter() << ", midpoint is located at (" << midPoint().getX() << ", " << midPoint().getY() << ")" << endl;
}
输出需要
Enter the name of the first rectangle: rec hi
Enter hi's bottom left x and y coords: 1 1
Enter hi's length and height: 2 2
Thank you! Enter the name of the next rectangle: stop
You have 1 rectangle(s) in your list:
Rectangle 'hi': Location is (1, 1), Length is 2, Height is 2; Area is 4, Perimeter is 8, Midpoint is located at (2, 2)
After scale by 3: Location is (-1, -1), Length is 6, Height is 6; Area is 36, Perimeter is 24, Midpoint is located at (2, 2)
但输出正确
Enter the name of the first rectangle: rec hi
Enter hi's bottom left x and y coords: 1 1
Enter hi's length and height: 2 2
Thank you! Enter the name of the next rectangle: Invalid input. Type 'rec' following by the name or 'stop' if done.
Try again!
Enter the name of the next rectangle: stop
You have 1 rectangle(s) in your list:
Rectangle 'hi': Location is (1, 1), length is 2, height is 2; Area is 4; perimeter is 12, midpoint is located at (2, 2)
After scale by 3: Location is (0, 0), length is 6, height is 6; Area is 36; perimeter is 36, midpoint is located at (3, 3)
我很感激任何帮助。我真的不想拉另一个更黑的人，我已经完成了大部分工作！非常感谢！
答案 0 :(得分：0)
如果你打算在中间点缩放Rectangle，那么你函数中的逻辑是不正确的。试试这个：
void Rectangle::scaleBy3()
{
double mx = blPoint.getX() + 0.5 * length;
double my = blPoint.getY() + 0.5 * height;
length = 3 * length;
height = 3 * height;
// Mid point remains exactly at the same location.
// Move the lower left corner so that it is offset from
// the mid point by half the length and half the width.
blPoint.setX( mx - 0.5*length);
blPoint.setY( my - 0.5*height);
}
<强>更新
您用来读取名称的逻辑是有问题的。看看How to allow user to do input more than twice?