计算值许多值与许多算术运算符C++

Question

1. #ifndef CALC_H 
   #define CALC_H 
   
   
   class calc 
   { 
       double numb1; 
       double numb2; 
       public: 
        calc(); 
        void FUN_SUM(); 
        void FUN_Subtraction(); 
        void FUN_Multiplication(); 
        void FUN_Division(); 
        void FUN_Power(); 
        void FUN_Squareroot(); 
        void FUN_Switch(); 
        void FUN_Loob(); 
   
   }; 
   
   #endif // CALC_H 
   
   
   
   #include "calc.h" 
   #include <iostream> 
   #include <cmath> 
   using namespace std; 
   calc::calc() 
   { 
       numb1 = 0; 
       numb2 = 0; 
   } 
   void calc::FUN_SUM() 
   { 
       cout << "Enter number 1 " << endl; 
       cin >> numb1; 
       cout << "Enter number 2 " << endl; 
       cin >> numb2; 
       double Result_Of_Sum; 
       Result_Of_Sum = numb1+numb2; 
       cout << "The result of Sum = " << Result_Of_Sum << endl; 
   
   
   } 
   
   void calc::FUN_Subtraction() 
   { 
       cout << "Enter number 1 " << endl; 
   cin >> numb1; 
   cout << "Enter number 2 " << endl; 
   cin >> numb2; 
   double Result_Of_Subtraction; 
   Result_Of_Subtraction = numb1 - numb2; 
   cout << "The result of Subtraction = " << Result_Of_Subtraction << endl; 
   } 
   void calc::FUN_Multiplication() 
   { 
       cout << "Enter number 1 " << endl; 
       cin >> numb1; 
       cout << "Enter number 2 " << endl; 
       cin >> numb2; 
       double Result_Of_Multiplication; 
       Result_Of_Multiplication = numb1*numb2; 
       cout << "The result of Multiplication = " << Result_Of_Multiplication << endl; 
   
   } 
   
   void calc::FUN_Division() 
   { 
       cout << "Enter number 1 " << endl; 
       cin >> numb1; 
       cout << "Enter number 2 " << endl; 
       cin >> numb2; 
       double Result_Of_Division ; 
       Result_Of_Division = numb1/numb2; 
       cout << "The result of Division = " << Result_Of_Division << endl; 
   } 
   
   void calc::FUN_Power() 
   { 
       cout << "Enter number 1 " << endl; 
   cin >> numb1; 
   cout << "Enter number 2 " << endl; 
   cin >> numb2; 
   double Result_Of_Power; 
   Result_Of_Power = pow(numb1,numb2); 
   cout << "The result of Power = " << Result_Of_Power << endl; 
   } 
   
   void calc::FUN_Squareroot() 
   { 
       cout << "Enter the tow number you want Square root \n"; 
       cin >> numb1; 
   
       double Result_Of_Square_root; 
       Result_Of_Square_root = sqrt(numb1); 
       cout << "The result of Square root = " << Result_Of_Square_root << endl; 
   } 
   void calc::FUN_Switch() 
   { 
   int S; 
       cout << "Enter the number you operator do you want do it " << endl; 
       cout << "1- Addition" << endl; 
       cout << "2- Subtraction" << endl; 
       cout << "3- Multiplication" << endl; 
       cout << "4- Division" << endl; 
       cout << "5- Power" << endl; 
       cout << "6- Square Root" << endl; 
        cout << "7- Exit" << endl; 
       cin >> S; 
   
       switch (S) 
       { 
       case 1: 
   
        FUN_SUM(); 
        break; 
   
       case 2: 
   
        FUN_Subtraction(); 
        break; 
   
       case 3: 
   
        FUN_Multiplication(); 
        break; 
   
       case 4: 
   
        FUN_Division(); 
        break; 
   
       case 5: 
   
        FUN_Power(); 
        break; 
   
       case 6: 
   
        FUN_Squareroot(); 
        break; 
   
       default : 
        break; 
   
       } 
   } 
   
   void calc::FUN_Loob() 
   { 
       char L; 
   
       do 
       { 
   
        FUN_Switch(); 
   
   cout << "Do you want do another operator ('y' or 'n'?) \n"; 
        cin >> L; 
   if (L== 'y' || L=='Y' || L=='n' || L=='N') 
   
       continue; 
   else 
       cout << "you are enter roang later\n"; 
   
       } 
   
       while (L == 'Y' || L == 'y'); 
   
   } 
   
   
   #include <iostream> 
   #include "calc.h" 
   using namespace std; 
   
   int main() 
   { 
       cout << "Welcome to my simple Calculator\n"; 
   calc simple_calc; 
   
   simple_calc.FUN_Loob(); 
   cout << "\n Tank you for use my App :) :) " << endl; 
   
   return 0; 
   } 
   

我的问题是如何我可以使用户计算值的任何值与像普通计算器运营

例如1 + 9 * 8-1 + 5我希望我的程序可以这样做，但我不知道怎么做？ :(:(

Answer 1

编写计算器不是一件容易的事，因为有更多的参与：

1. 运算符优先级
2. 分组
3. 表达式的评估

运算符优先级
运算符优先级是运算的分组，例如执行所有乘法加减之前的分割和分割。计算器程序应该处理没有括号（分组）的优先级。

分组
更高级的计算器将允许使用圆括号对表达式进行分组。计算器应该能够评估最内在的表达并向外工作。

求表达式
这意味着允许多于1位的数字，和数字和符号之间的空格。此外，一旦表达式解析，它需要评估。计算器应根据操作（由用户指定）调用适当的功能。

我建议你允许用户输入一个表达式，并且你的程序以字符串的形式读取它。然后您的程序将解析字符串，然后评估表达式。

搜索网络和StackOverflow的“C++计算器”的例子。