c++ - 类中的静态函数和数组

Question

我在尝试编译下面的代码时遇到了 5 个错误。就像:它们主要指向 static string rzym 和 static int arab。主要错误: 在 arab2rzym 函数中:

 - : invalid use of member ‘RzymArab::arab’ in static member function
 - : error: from this location
 - : error: invalid use of member ‘RzymArab::arab’ in static member function  
 - : invalid use of member ‘RzymArab::rzym’ in static member function
 - : cannot declare member function ‘static std::string RzymArab::arab2rzym(int)’ to have static linkage [-fpermissive]

代码如下:

#include <iostream>
#include <string>

using namespace std;

class RzymArab 
{
    private:
            string rzym[13] = {"I","IV","V","IX","X","XL","L","XC","C","CD","D","CM","M"};
            int arab[13] = {1,4,5,9,10,40,50,90,100,400,500,900,1000};
    public:
        static int rzym2arab(string);
        static string arab2rzym(int);
};

static string RzymArab::arab2rzym(int x) 
{
    int i=12;
    string s="";

    while(x>=1) 
    {
        if(x>=arab[i])
            {
            x-=arab[i];
            s=s+rzym[i];
            }
        else
            i-=1;
    }
    return s;
}       

int main() 
{
    string x;
    x=RzymArab.arab2rzym(1164);
    cout<<x<<endl;
    return 0;
} 

如果能提供帮助，我将不胜感激!我做了一些事情，但仍然有很多错误。我想在不创建对象的情况下使用类中的元素。有什么想法吗？

Answer 1

您不能从静态成员函数访问非静态类成员变量。您还需要将它们设为静态:

class RzymArab {
private:
    static string rzym[13];
    static int arab[13];
public:
   static int rzym2arab(string);
   static string arab2rzym(int);
};

还有那些需要单独定义(通常在你的类的.cpp文件中):

string RzymArab::rzym[13] = 
    {"I","IV","V","IX","X","XL","L","XC","C","CD","D","CM","M"};
int RzymArab::arab[13] = {1,4,5,9,10,40,50,90,100,400,500,900,1000};

另外请注意，您不要使用 static 关键字作为静态函数的(非内联)定义(这是无效语法)。只写:

string RzymArab::arab2rzym(int x) {
     // ...
}

查看完全修复、可编译和运行的示例 here请。