所以这是我的代码：
#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:
// member functions
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 scaleBy2();
void display() const;
};
// FUNCTION PROTOTYPES GO HERE:
void welcome();
bool read_rec(const string promptName, const string errorInvalid, const string errorUsed, string & inName, vector<Rectangle> & list);
void read_coord(const string promptPoint, double & x, double & y);
void read_length(const string promptLength, double & inLength, double & inHeight);
void add_rec(const string Name, double x, double y, double inLength, double inHeight, vector<Rectangle> & list);
int main()
{
// Define your local variables, e.g. a vector of class Rectangle
Rectangle rec;
vector<Rectangle> list;
string prompt1stName = "Enter the name of the first rectangle: ";
string promptName = "Enter the name of the next rectangle: ";
string errorInvalid = "Invalid input. Type 'rec' following by the name or 'stop' if done.";
string errorUsed = "This name is already being used!";
string inName;
string Name;
// Display welcome banner
welcome();
/* Prompt user for first rectangle or 'stop' */
bool read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
// WHILE user input is invalid
while (read == false)
{
// Display "Try again! "
cout << "Try again! " << endl;
read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
}
// IF user input is not 'stop'
if (inName != "stop")
{
// Extract rectangle name from user input
int a = inName.length() - 4;
Name = inName.substr(4, a);
// Prompt for bottom left point
double x, y;
string promptPoint = "Enter " + Name + "'s bottom left x and y coords: ";
read_coord(promptPoint, x, y);
// Prompt for length and height
double inLength, inHeight;
string promptLength = "Enter " + Name + "'s length and height: ";
read_length(promptLength, inLength, inHeight);
// Add rectangle to the rectangle list
add_rec(Name, x, y, inLength, inHeight, list);
}
/* Prompt user for next rectangle or 'stop' */
// WHILE user input not 'stop'
while (inName != "stop")
{
// Display "Thank you! "
cout << "Thank you! ";
bool read = read_rec(promptName, errorInvalid, errorUsed, inName, list);
// WHILE user input is invalid while (read == false)
{
// Display "Try again! "
cout << "Try again! " << endl;
read = read_rec(promptName, errorInvalid, errorUsed, inName, list);
}
// IF user input is not 'stop'
if (inName != "stop")
{
// Extract rectangle name from user input
int a = inName.length() - 4;
Name = inName.substr(4, a);
// Prompt for bottom left point
double x, y;
string promptPoint = "Enter " + Name + "'s bottom left x and y coords: ";
read_coord(promptPoint, x, y);
// Prompt for length and height
double inLength, inHeight;
string promptLength = "Enter " + Name + "'s length and height: ";
read_length(promptLength, inLength, inHeight);
// Add rectangle to the rectangle list
add_rec(Name, x, y, inLength, inHeight, list);
}
}
// IF the rectangle list is not empty
if (list.size() != 0)
{
// Display all rectangles in the rectangle list
int rec_num = 0;
int i = 1;
while (i< list.size())
{
rec_num++;
i++;
}
cout << "You have " << rec_num+1 << " rectangle(s) in your list: ";
cout << endl;
for (int i = 0; i < list.size(); i++)
{
cout << "Rectangle '" << list[i].getName() << "' : ";
list[i].display();
list[i].scaleBy2();
cout << " After scale by 2: ";
list[i].display();
cout << endl;
}
}
// ELSE
else
{
// Display that no rectangles are in the list
cout << "You have no rectangles in your list." << endl;
}
return 0;
}
// FUNCTION DEFINITIONS GO HERE:
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_rec(const string promptName, const string errorInvalid, const string errorUsed, string & inName, vector<Rectangle> & list)
{
cout << promptName;
getline(cin, inName);
if (inName == "stop")
{
return(true);
}
else if (inName.substr(0,4) != "rec ")
{
cout << errorInvalid;
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 << errorUsed;
return(false);
}
}
}
void read_coord(const string promptPoint, double & x, double & y)
{
cout << promptPoint;
cin >> x;
cin >> y;
}
void read_length(const string promptLength, double & inLength, double & inHeight)
{
cout << promptLength;
cin >> inLength;
cin >> inHeight;
cout << endl;
while (inLength <= 0 || inHeight <= 0)
{
cout << "Make length and height positive values. Try again.";
cout << promptLength;
cin >> inLength;
cin >> inHeight;
cout << endl;
}
}
void add_rec(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);
}
// CLASS MEMBER FUNCTION DEFINITINOS GO HERE:
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
{
// area = length * height
return(length * height);
}
double Rectangle::perimeter() const
{
// perimeter = 2 * (length + height);
return(2 * (length + height));
}
Point Rectangle::midPoint() const
{
Point midPoint;
double mx = blPoint.getX() + 0.5 * length;
double my = blPoint.getY() + 0.5 * height;
midPoint.setX(mx);
midPoint.setY(my);
return(midPoint);
}
void Rectangle::scaleBy2()
{
double midx = blPoint.getX() + 0.5 * length;
double midy = blPoint.getY() + 0.5 * height;
double newblPx = midx - length;
double newblPy = midy - height;
length = 2*length;
height = 2*height;
blPoint.setX(newblPx);
blPoint.setY(newblPy);
}
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;
}
我现在对程序的唯一问题是它总是输出“无效输入。输入'rec'后跟名称或'stop'如果完成。”，我不知道如何改变它。当你在rec fire和rec fire中输入一个重复的答案时，它会说rec fire已被使用，然后继续提示该矩形，而不是要求另一个名字。任何帮助将非常感谢!!
答案 0 :(得分：1)
这是错误的
/* Prompt user for first rectangle or 'stop' */
bool read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
// WHILE user input is invalid
while (read == false)
{
// Display "Try again! "
cout << "Try again! " << endl;
bool read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
}
你有两个读取变量，while条件中的read变量指的是声明 first 的读取变量，从不使用声明为second的读取变量。你想要的是这个
/* Prompt user for first rectangle or 'stop' */
bool read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
// WHILE user input is invalid
while (read == false)
{
// Display "Try again! "
cout << "Try again! " << endl;
read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
}
现在你只有一个读变量。这说明了我想到的第二个错误。
另一种编码方式就是这样
for (;;)
{
bool read = read_rec(prompt1stName, errorInvalid, errorUsed, inName, list);
if (read)
break;
cout << "Try again! " << endl;
}
在我看来，这种循环更好，因为它没有对read_rec的重复调用，所以使用这种循环方式你所犯的错误是不可能的。