静态映射初始化 [英] static map initialization

问题描述

我有以下代码：我有以下代码：

I have the following code :I have the following code:

//MyClass.h
class MyClass {
public:
      typedef std::map<std::string, int> OpMap;
      static OpMap opMap_;


     //methods
};

//MyClass.cpp
//Init opMap_
MyClass::opMap_["x"] = 1; //compilation error

如何对任何case初始化（静态）opMap _？

How can I any case initialize (static) opMap_?

推荐答案

如果你使用C ++ 11，你可以使用初始化列表：

If you're using C++11, you could use initializer lists:

//MyClass.h
class MyClass {
public:
      typedef std::map<std::string, int> OpMap;
      static OpMap opMap_;
};

//MyClass.cpp
MyClass::OpMap MyClass::opMap_ = { 
    { "x", 1 }
}; 

如果您无法访问支持C ++ 11标准的编译器，请执行以下操作：

If you don't have access to a compiler that supports the C++11 standard, you could do the following:

//MyClass.h
class MyClass {
public:
      typedef std::map<std::string, int> OpMap;
      static OpMap opMap_;
private:
      static OpMap init_map() {
          OpMap some_map;
          some_map["x"] = 1;
          return some_map;
      }
};

//MyClass.cpp
MyClass::OpMap MyClass::opMap_ = init_map();

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