将getline（）字符串拆分为多个int和char变量？

Question

我在理解如何正确操作字符串时遇到了一些麻烦。下面的程序是一个简单的计算器。

当我通过多个cin语句将输入直接放入变量时，一切正常。现在，我想用getline（）作为字符串输入，并将数字/运算符存储在getline（）中的现有变量中。

我的主要问题是我想让程序识别2+2和2 + 2。

#include <iostream> 
#include <string> 
#include <sstream> 

using namespace std; 

int main() 
{ 
    int Num1, Num2, Num3 = 0, result; 
    char Operator1, Operator2 = 0; 
    string input, in1; 

    cout << "Enter your equation on one line.\n"; 
    getline(cin, input); 


    //this is where getline needs to be manipulated into Num1/2/3 and Operator1/2 

    cout << input; 


    if (Operator2 != 0) 
    { 
     if (Operator1 == '+') 
     { 
      if (Operator2 == '+') 
      { 
       result = Num1 + Num2 + Num3; 
       cout << "I made it to A!"; 
      } 
      else if (Operator2 == '-') 
      { 
       result = Num1 + Num2 - Num3; 
      } 
      else if (Operator2 == '/') 
      { 
       result = Num1 + Num2/Num3; 
      } 
      else if (Operator2 == '*') 
      { 
       result = Num1 + Num2 * Num3; 
      } 
     } 
     else if (Operator1 == '-') 
     { 
      if (Operator2 == '+') 
      { 
       result = Num1 - Num2 + Num3; 
      } 
      else if (Operator2 == '-') 
      { 
       result = Num1 - Num2 - Num3; 
      } 
      else if (Operator2 == '/') 
      { 
       result = Num1 - Num2/Num3; 
      } 
      else if (Operator2 == '*') 
      { 
       result = Num1 - Num2 * Num3; 
      } 
     } 
     else if (Operator1 == '/') 
     { 
      if (Operator2 == '+') 
      { 
       result = Num1/Num2 + Num3; 
      } 
      else if (Operator2 == '-') 
      { 
       result = Num1/Num2 - Num3; 
      } 
      else if (Operator2 == '/') 
      { 
       result = Num1/Num2/Num3; 
      } 
      else if (Operator2 == '*') 
      { 
       result = Num1/Num2 * Num3; 
      } 
     } 
     else if (Operator1 == '*') 
     { 
      if (Operator2 == '+') 
      { 
       result = Num1 * Num2 + Num3; 
      } 
      else if (Operator2 == '-') 
      { 
       result = Num1 * Num2 - Num3; 
      } 
      else if (Operator2 == '/') 
      { 
       result = Num1 * Num2/Num3; 
      } 
      else if (Operator2 == '*') 
      { 
       result = Num1 * Num2 * Num3; 
      } 
     } 
     else 
     { 
      cout << "I don't recognize that operator. Did you type in one of these?: + - * /"; 
     } 
    } 
    else if (Operator2 == 0) 
    { 
     if (Operator1 == '+') 
    { 
      result = Num1 + Num2; 
    } 
     else if (Operator1 == '-') 
    { 
      result = Num1 - Num2; 
    } 
     else if (Operator1 == '*') 
    { 
      result = Num1 * Num2; 
    } 
     else if (Operator1 == '/') 
    { 
      result = Num1/Num2; 
    } 
     else 
    { 
     cout << "I don't recognize that operator. Did you type in one of these?: + - * /"; 
    } 

     result = Num1 + Num2; 
     cout << "I made it to B!"; 
    } 


    cout << "Your result is: " << result << endl << endl; 

    return 0; 
} 

任何帮助将不胜感激，但我更喜欢对工作代码的解释。

我对程序的数学逻辑或using namespace std方面不感兴趣。

Answer 1

首先，您应该问自己，是否有必要存储整个字符串，而不是直接对变量使用cin，就像您之前所说的那样。

如果你确实想要存储整个字符串（如你的回响，现在这样做），你可以考虑使用一个字符串流（您已包括您的文件sstream，出于某种原因）：

getline(cin, input); 

std::istringstream iss(input); 
// you can now use iss just as cin. 
// I'm not sure exactly what you want to do, but it would look something like this: 
iss >> num1; 
iss >> Operator1; 
iss >> num2; 

cout << input;