Question

大家好，我不是这方面的专家，所以请原谅我的倾倒技巧。我完成了我的程序，它工作正常（计算器）。问题是，现在我不知道在哪里找到while循环与布尔函数相结合，一旦完成任务就重复该过程（一旦程序完成数学运算）。任何帮助，评论或建议将不胜感激。谢谢。！！

 #include <iostream>  
 #include <math.h> 
 #include <cmath>


 int main()
 {

 double a=0.0;
 double b=0.0;
 double c=0.0;
 bool repeat = true;


do {
using namespace std;
int x;

cout << "**********************************" << endl;
cout << "|                                |" << endl;
cout << "| 0 - Quit                       |" << endl;
cout << "| 1 - Add                        |" << endl;
cout << "| 2 - Subtract                   |" << endl;
cout << "| 3 - Divide                     |" << endl;
cout << "| 4 - Multiply                   |" << endl;
cout << "| 5 - Raise X to the power Y     |" << endl;
cout << "| 6 - Sine ( x )                 |" << endl;
cout << "| 7 - Cosine ( x )               |" << endl;
cout << "| 8 - Tangent ( x )              |" << endl;
cout << "**********************************" << endl;
cout << "Enter a selection, please: " << endl; 
cin >> x;




switch (x)
{


{
case 1:
cout << " Enter the first value" <<endl;
cin >> a ;
cout << " Enter second value " << endl;
cin >> b; 
c=a+b;
cout << "The addition of " << a << " and "<< b << "is" << c << endl;

break;
bool repeat = true;
 }



 {
case 2:
cout << " Enter the first value" << endl;
cin >> a ;
cout << " Enter the second value " << endl;
cin >> b; 
c=a-b;
cout << "The subtraction of " << a << " and " << b << " is: " << c << endl;

break;
bool repeat = true;
}


{
case 3:
cout << " Enter the first value" <<endl;
cin >> a ;
cout << " Enter the second value " << endl;
cin >> b; 
c=a/b;
cout << " The division os " << a << " and " << b << "is" << c << endl;

break;
bool repeat = true;
 }


 {
case 4:
cout << " Enter the first value" <<endl;
cin >> a ;
cout << " Enter the second value " << endl;
cin >> b; 
c=a*b;
 cout << " The product of " << a << " times " << b << " is " << c << endl;
 break;
 bool repeat = true;
 }

  {
  case 5:
 cout << " Enter the value to be exponentiated " <<endl;
 cin >> a ;
 cout << " Enter the exponent" << endl;
 cin >> b; 
 c= pow(a,b);
 cout << a << " Rased to the power of " << b << " is: " << c << endl;

 break;
 bool repeat = true;
  }


  { 
  case 6:
  cout << " Enter the value that you want the sine to be taken of" <<endl;
  cin >> a ;
  c=sin(a);
  cout << " The sine of " << a << " is: " << c << endl ;

  break;
  bool repeat = true;
   }

   {
  case 7:
  cout << " Enter the value that you want the cosine to be taken of" <<endl;
  cin >> a ;
  c=cos(a);
  cout << " The cosine of " << a << " is: " << c << endl ;
   break;
  bool repeat = true;
   }


   {
  case 8:
   cout << " Enter the value that you want the tangent to be taken of"                           <<endl;
  cin >> a ; 
  c=tan(a);
  cout << " The tangent of " << a << " is: " << c << endl ;

  break;
  bool repeat = true;
   } 


   {
   case 0:
   cout << "Ending the program" << endl;
   return 0;}

   break;
   bool repeat = true;
     }
    } while (repeat = true );
     return 0;  
     }

Answer 1

所以这里很少。

致电

using namespace std;

只相信 - 这是个坏主意;

在if（）或while（）之类的条件下，使用operator ==而不是=。因为＆＃34; =＆＃34; - 是assigne操作员，返回值取决于操作的成功。并且＆＃34; ==＆＃34;是比较运算符。

噢，又想到了一个误区。使用bool rezult = true;是错的。你应该使用rezult = true;因为每次编写类型说明符时都会在case的上下文中创建局部变量，这不会影响在main中声明的rezult

我对你的问题的看法几乎没有变化：从：

do{ 
int x;
...
case 0:
   cout << "Ending the program" << endl;
   return 0;}

   break;
   bool repeat = true;
     }
    } while (repeat = true );

到

do{ 
 int x;
 ...

 case 0:
  cout << "Ending the program" << endl;
  repeat = false;}
  break;
  }
} while (repeat == true);

如果你需要更多的计算，你可以把它包装成新的cicle，如：

while(new_condtion == true) {
  do {
  ...
  } while(repeat == true);
  //change new_condtion
}

Answer 2

请勿在切换案例中重新定义repeat。这会创建一个名为repeat的不同变量，虽然它具有相同的名称，但它不是在循环之前定义的名为repeat的变量。这是您将表单bool repeat = true;的定义复制到多个位置时获得的结果。

循环的继续条件（repeat = true）也将永远循环。比较是两个=符号，而不是一个。

while循环和布尔函数

2 个答案: