评估字符串到类变量 [英] Evaluate string to class variable

问题描述

我需要评估一个字符串，以便我可以为类变量赋值：

类：

  class DATACLASS {
 public：
 double variable1，variable2，variable3; 
}; 
  

void init（）：

  void init（）
 {
 DATACLASS * d = new DATACLASS; 
 std :: string ssList [3] = {variable1，
variable2，
variable3}; 
 for（unsigned i = 0; i <3; ++ i）
 {
 std :: stringstream ss; 
 ss<< ssList [i]; 
 //ss.str（）。c_str（）对应于variable1，variable2，variable3
 mxArray * array_ptr = mexGetVariable（base，ss.str ））; 
 double pr =（double）mxGetPr（array_ptr）[0]; 
 //如何在这里做同样的事情？ 
 //我想要评估的东西
 // data-> ssList [i] = pr; 
 //或更精确地
 // data-> variable1 = pr; 
 //但是从下面的ss字符串（但这不起作用）
 data-> ss.str（）。c_str（）= pr; 
} 
  

当尝试这样做时会出现这种错误： p>

 错误C2039：'ss'：不是'DATACLASS'的成员
  pre> 
 
解决方案
没有大量努力，最合理的方法就是下面这样。你可以使用宏，函数，容器，模板，指针/引用等抽象出一些东西，但这是基本的要点。我不建议这样做，承诺时间，除非你有一个令人信服的理由。您的最终目标是什么？
  class DATACLASS {
 public：
 double variable1，variable2，variable3; 
}; 
 
 void init（）
 {
 DATACLASS * d = new DATACLASS; 
 std :: string ssList [3] = {variable1，
variable2，
variable3}; 
 for（unsigned i = 0; i <3; ++ i）
 {
 std :: stringstream ss; 
 ss<< ssList [i]; 
 //ss.str（）。c_str（）对应于variable1，variable2，variable3
 mxArray * array_ptr = mexGetVariable（base，ss.str ））; 
 double pr =（double）mxGetPr（array_ptr）[0]; 
 if（ss.str（）==variable1）
 data-> variable1 = pr; 
 else if（ss.str（）==variable2）
 data-> variable2 = pr; 
 else if（ss.str（）==variable3）
 data-> variable3 = pr; 
} 
} 
  
 
I need to evaluate a string so i can assign a value to a class variable :

Class :
class DATACLASS {
public:
    double variable1, variable2, variable3;
};
The void init() :
void init() 
{
    DATACLASS *d = new DATACLASS;
    std::string ssList[3] = {"variable1", 
                             "variable2", 
                             "variable3"};                        
    for(unsigned i = 0; i < 3; ++i)
    {
      std::stringstream ss;
      ss << ssList[i];
      //ss.str().c_str() correspond to "variable1", "variable2", "variable3"
      mxArray *array_ptr = mexGetVariable("base", ss.str().c_str());
      double pr = (double)mxGetPr(array_ptr)[0];
      // How to make the same thing here?
      // I would like to have something that would evaluate
      // data->ssList[i] = pr;
      // or more precisely      
      // data->variable1 = pr;
      // but from the ss string like below (but this doesn't work)
      data->ss.str().c_str() = pr;
    }
I get this kind of error when trying to do it this way :
error C2039: 'ss' : is not a member of 'DATACLASS'

解决方案
The closest you'll reasonably come without a huge amount of effort is something like the following. You could abstract away some things using macros, functions, containers, templates, pointers/references, etc., but this is the basic gist. I wouldn't suggest doing this and committing the time to it unless you have a compelling reason. What is your end goal?
class DATACLASS {
public:
    double variable1, variable2, variable3;
};

void init() 
{
    DATACLASS *d = new DATACLASS;
    std::string ssList[3] = {"variable1", 
                             "variable2", 
                             "variable3"};                        
    for(unsigned i = 0; i < 3; ++i)
    {
      std::stringstream ss;
      ss << ssList[i];
      //ss.str().c_str() correspond to "variable1", "variable2", "variable3"
      mxArray *array_ptr = mexGetVariable("base", ss.str().c_str());
      double pr = (double)mxGetPr(array_ptr)[0];
      if(ss.str() == "variable1")
        data->variable1 = pr;
      else if(ss.str() == "variable2")
        data->variable2 = pr;
      else if(ss.str() == "variable3")
        data->variable3 = pr;
    }
}


                        
这篇关于评估字符串到类变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！