Question

我在fixed.cpp中创建了一个类声明文件，作为fixed.hpp和类定义。当我在main函数中创建一个对象时。编译器告诉我该类未声明。但我想我做到了。有什么想法或帮助吗？感谢。

这是main.cpp：

    #include <iostream>
    #include <istream>
    #include <ostream>
    #include <sstream>
    #include <stdexcept>

    #include "test.hpp"
    #include "fixed.hpp"

    int main(int argc, char *argv[])
    { using namespace std;
      fixed f1;
      cout<<f1.value()<<endl;
    }

这是fixed.hpp：

    #ifndef FIXED_HPP_
    #define FIXED_HPP_

    typedef float value_type ; 

    class fixed
    {
     public:
       fixed();
       fixed(value_type integer, value_type fraction); 
       fixed(double val);

       void as_string();
       value_type integer();
       value_type fraction();
       value_type value();
       static const int places=4;    
       static const int places10=10000;  //scale factor

     private:
       value_type integer_;
       value_type fraction_;   
       //value_type result_;

    };

这是fixed.cpp：

    #include "fixed.hpp"

    #include <iostream>
    #include <ostream>
    #include <stdexcept>
    #include <string>


    using namespace std;

    //static const value_type fixed::places(4);
    //static const value_type fixed::places10(10000);
    fixed::fixed():integer_(0), fraction_(0){}

    fixed::fixed(value_type                     integer,value_type                         fraction):integer_(integer), fraction_(fraction) 
           {try
       {
        if (fraction_ <0)                          
           throw invalid_argument("Invalid argument. Must be positive.");
       }
    catch (exception& e)
      {
        cout <<"\n"<< e.what() << endl;
      }
     while (fraction_>= places10)
        {
         if(int(fraction_)%10 >=5 && fraction_< (places10*10) )
            fraction_=fraction_/10+1;               
         else
            fraction_/=10;
        }

     //result_ = integer_ + fraction_/places10;  //??
   } 

    fixed::fixed(double val):integer_(int (val)), fraction_(         (val- int(val))*places10) 
           { if (val <0)
        {    val = val*(-1);
             if ( int(val*places10*10)%10>=5)
              fraction_ = (fraction_*(-1) +1)*(-1);
        }     
     else
         {
          if (int(val*places10*10)%10>=5)
              fraction_ = fraction_ +1;
         }

     //result_ = integer_ + fraction_/places10;  //??
   }

    void fixed::as_string()
           {    string str;
                string str2;
                while( (int(integer_)/10) >=0 and int(integer_)>0 )
             {
             str.push_back(int(integer_)%10 + 48);
             integer_ = integer_/10;
             //cout<<str<<endl;
             }
        //cout<<"String format: "<<str<<endl;
        reverse(str.begin(), str.end());
        //cout<<"Reversed format: "<<str<<endl;
        str.push_back('.');
        //cout<<"New string: "<<str<<endl;
        while( (int(fraction_)/10 )>=0 and int(fraction_)>0)
             {
             str2.push_back(int(fraction_)%10 + 48);
             fraction_ = fraction_/10;
             //cout<<str<<endl;
             }
        //cout<<"String format: "<<str<<endl;
        reverse(str2.begin(), str2.end());
        str.append(str2);
        cout<<"String representation: "<<str<<endl;
           }


    value_type fixed::value()
         {
          return   integer_ + fraction_/places10;     
         }
    value_type fixed::integer()
         {
          return integer_;
         }
    value_type fixed::fraction()
         {
          return fraction_;
         }

Answer 1

我尝试编译代码，这是唯一的重大错误：

fixed.cpp: In member function ‘void fixed::as_string()’:
fixed.cpp:63:35: error: ‘reverse’ was not declared in this scope

我通过使用

修复了这个问题

#include <algorithm>

in fixed.cpp

C ++：错误：类未声明（首次在此函数中使用）。但我在hpp文件中声明了它

1 个答案: