왜 무한 루프가 되는가

Question

#include <iostream> 
#include <math.h> 
using namespace std; 

int main() { 
    double radius = 0.00; 
    double height = 0.00; 
    double width = 0.00; 
    double side = 0.00; 
    double Area = 0.00; 
    const double PI = atan(1.0)*4; 
    string input = "none"; 

    while (input != "0") { 
     cout << "Shape Menu: \n (r) rectangle \n (s) square \n (c) circle \n (0) exit" << endl; 
     cin >> input; 
     if (input == "r"){ 
      cout << "Please enter a floating point value for the height of the rectangle." << endl; 
      cin >> height; 
      cout << height; 
      while (height <= 0) 
      { 
       cin.clear(); 
       cin.ignore(1000, '\n'); 
       cout << "Your input was invalid. Please input a floating point value greater than 0."; 
       cin >> height; 
      } 
      cout << "Please enter a floating point value greater than 0 for the width of the rectangle." << endl; 
      cin >> width; 
      while (width <= 0) 
      { 
       cin.clear(); 
       cin.ignore(1000, '\n'); 
       cout << "Your input was invalid"; 
       cin >> width; 
      } 
      Area = height*width; 
      cout << "The area of a rectangle with those dimensions is " << Area << "units squared." << endl; 
     } 

     else if(input == "s"){ 
      cout << "Please enter a floating point value for the length of the side." << endl; 
      cin >> side; 
      if (cin.fail()) 
       cout << "Please enter a floating point value."; 
      Area = side*side; 
      cout << "The area of a square with those dimensions is " << Area << "units squared" << endl; 
     } 

     else if(input == "c"){ 
      cout << "Please enter a floating point value for the length of the radius." << endl; 
      cin >> radius; 
      if (cin.fail()) 
       cout << "Please enter a floating point value."; 
      Area = radius*radius*PI; 
      cout << "The area of a circle with those dimensions is " << Area << "units squared." << endl; 
     } 

     else if(input == "0"){ 
      break; 
     } 

     else{ 
      cout << "Your input does not match one of the options suggested. Please type r, s, c to get the area of a shape, or type 0 to exit." << endl; 

     } 
     } 

    return 0; 
} 

사용자가 모양 메뉴에서 선택하고 각 유형에 대한 특정 입력을 요구하여 영역을 결정하도록 요청하는 프로그램을 작성하려고합니다. 지금 내가 겪고있는 문제는 사람들이 숫자가 아닌 반지름이나 높이와 너비에 대한 대답을 입력 할 때 오류를 발생시키는 방법을 알아 내려고합니다. 직사각형에 대해 작성하려고 시도한 오류는 초기 부정확 한 입력에 대해 작동했지만 사용자가 다른 모양을 선택하라는 메시지가 나타나면 입력 오류가 다시 발생하면 무한 루프가 시작됩니다.

Answer 1

cin.clear() 및 cin.ignore (1000, '\ n')를 사용하여 사각형 입력의 유효하지 않은 입력을 건너 뛸 수 있지만, 다른 경우에는 그렇게하지 않는 것이 좋습니다. . 내가 의 (평방 용) 및 의 다시 입력하면

Answer 2

은 저를 위해, 당신의 코드는 루프에 갈 것입니다. 이 코드는 그렇지 않습니다. 입력이 끝나면 확인합니다.

#include <iostream> 
#include <math.h> 
using namespace std; 

int main() 
{ 
    double radius = 0.00; 
    double height = 0.00; 
    double width = 0.00; 
    double side = 0.00; 
    double Area = 0.00; 
    const double PI = atan(1.0)*4; 
    string input = "none"; 

    while (input != "0") 
    { 
     cout << "Shape Menu: \n (r) rectangle \n (s) square \n (c) circle \n (0) exit" << endl; 
     if (!(cin >> input)) 
     { 
      cout << "Break after reading input\n"; 
      break; 
     } 
     cout << "Input: <<" << input << ">>" << endl; 
     if (input == "r") 
     { 
      cout << "Please enter a floating point value for the height of the rectangle." << endl; 
      if (!(cin >> height)) 
      { 
       cout << "Break after reading height (1)\n"; 
       break; 
      } 
      cout << height; 
      while (height <= 0) 
      { 
       cin.clear(); 
       cin.ignore(1000, '\n'); 
       cout << "Your input was invalid. Please input a floating point value greater than 0."; 
       if (!(cin >> height)) 
       { 
        cout << "Break after reading height (2)\n"; 
        break; 
       } 
      } 
      cout << "Please enter a floating point value greater than 0 for the width of the rectangle." << endl; 
      if (!(cin >> width)) 
       break; 
      while (width <= 0) 
      { 
       cin.clear(); 
       cin.ignore(1000, '\n'); 
       cout << "Your input was invalid"; 
       if (!(cin >> width)) 
        break; 
      } 
      Area = height*width; 
      cout << "The area of a rectangle with those dimensions is " << Area << " units squared." << endl; 
     } 

     else if (input == "s") 
     { 
      cout << "Please enter a floating point value for the length of the side." << endl; 
      if (!(cin >> side)) 
      { 
       cout << "Break after reading length\n"; 
       break; 
      } 
      if (cin.fail()) 
       cout << "Please enter a floating point value."; 
      Area = side*side; 
      cout << "The area of a square with those dimensions is " << Area << " units squared" << endl; 
     } 

     else if (input == "c") 
     { 
      cout << "Please enter a floating point value for the length of the radius." << endl; 
      if (!(cin >> radius)) 
      { 
       cout << "Break after reading radius\n"; 
       break; 
      } 
      if (cin.fail()) 
       cout << "Please enter a floating point value."; 
      Area = radius*radius*PI; 
      cout << "The area of a circle with those dimensions is " << Area << " units squared." << endl; 
     } 

     else if (input == "0") 
     { 
      cout << "Break after reading zero\n"; 
      break; 
     } 

     else 
     { 
      cout << "Your input does not match one of the options suggested.\n" 
       << "Please type r, s, c to get the area of a shape, or type 0 to exit." << endl; 
     } 
    } 

    return 0; 
}