指定另一個std :: vector的std :: vector地址

Question

我正在編寫一個程序來平衡化學方程式。該程序通過獲取方程字符串，將其拆分爲基於等號的大小爲2的std :: vector，然後將左側separatedEquation[0]和右側separatedEquation[1]解析爲另一組std :: vector的leftHalf和rightHalf分別。

問題

我有一個函數方程:: filterEquation分析給separatedEquation的元素名稱。我想使用一個指向leftHalf或rightHalf地址的臨時向量。我知道這可能是令人困惑的，但這是我的代碼和我正在嘗試做的事情。我認爲我需要使用指針，但是我以前從來沒有必須使用指針，並且對它們沒有效率。

void Equation::filterEquation() 
{ 
    for(int i=0; i<separatedEquation.size(); i++) //i = index of separated equation 
    { 
     int index=0; 
     std::vector<std::string> equationHalf; 
     if(i==0) 
      equationHalf = leftHalf; //set equationHalf to the address of leftHalf 
     if(i==1) 
      equationHalf = rightHalf; //set equationHalf to the address of rightHalf 
     for (std::string::iterator it = separatedEquation[i].begin(); it!=separatedEquation[i].end(); ++it, index++) 
     { 
      //Elements are set up so that He = Helium, while H = Hydrogen. This separates the elements based upon upper and lowercae 
      bool UPPER_LETTER = isupper(separatedEquation[i][index]); //true if character is upperCase 
      bool NEXT_LOWER_LETTER = islower(separatedEquation[i][index+1]); //true if next is lowerCase 
      if (UPPER_LETTER)// if the character is an uppercase letter 
      { 
       if (NEXT_LOWER_LETTER) 
       { 
        std::string temp = separatedEquation[i].substr(index, 2);//add THIS capital and next lowercase 
        equationHalf.push_back(temp); // add temp to vector 
       } 

       else if (UPPER_LETTER && !NEXT_LOWER_LETTER) //used to try and prevent number from getting in 
       { 
        std::string temp = separatedEquation[i].substr(index, i); 
        equationHalf.push_back(temp); 
       } 
      } 
     } 
    } 

} 

Answer 1

在一般意義上，你將取代：

std::vector<std::string> equationHalf; 

... 

equationHalf = leftHalf // same for rightHalf 

與

std::vector<std::string>* equationHalf; 

... 

equationHalf = &leftHalf // same for rightHalf 

然後用equationHalf->取代equationHalf.任何實例。

雖然，你的情況，我會認真考慮重新考慮你的設計，比如打破了上equationHalf操作到功能，並把它傳遞給了vector參考，以在諸如void doStuff(std::vector<std::string> & equationHalf)操作代碼，然後只需調用doStuff(leftHalf)和doStuff(rightHalf)。