类的嵌套

class1.h文件中：


#ifndef CLASS1_H_
#define CLASS1_H_
#include <iostream>
#include <string>
class class1
{
public:
class class2
{
public:
class2();
class2(const class2 & src);
class2& operator = (const class2 & rhs);
private:
double class2Value;
std::string mString;
mutable int mNumber = 0;
};

class1();
class1(double value);
~class1();
private:
double class1Value;
}; 

#endif //CLASS1_H_

 

class1.cpp文件中：

#include "class1.h"

class1::class1()
:class1Value(0.0)
{

}
class1::class1(double value)
:class1Value(value)
{

}
class1::~class1()
{

}


class1::class2::class2()
:class2Value(0.0)
,mString("")
{    
mNumber++;
}
class1::class2::class2(const class2 & src)
{
mNumber++;
class2Value = src.class2Value;
mString = src.mString;
}
class1::class2& class1::class2::operator = (const class2 & rhs)
{
if(this == &rhs)
{
return *this;
}
class2Value = rhs.class2Value;
mString = rhs.mString;
mNumber = rhs.mNumber;
return *this;    
}

这里注意的是：在定义赋值运算符是的限定符class1::class2& class1::class2::operator = (const class2 & rhs)十分不便；

所以可以这样：

使用类别名称重命名，这样容易管理,在.cpp文件最上边定义：using sClass = class1::class2;

#include "class1.h"
using sClass = class1::class2;
class1::class1()
:class1Value(0.0)
{

}
class1::class1(double value)
:class1Value(value)
{

}
class1::~class1()
{

}


sClass::class2()
:class2Value(0.0)
,mString("")
{    
mNumber++;
}
sClass::class2(const class2 & src)
{
mNumber++;
class2Value = src.class2Value;
mString = src.mString;
}
sClass& sClass::operator = (const class2 & rhs)
{
if(this == &rhs)
{
return *this;
}
class2Value = rhs.class2Value;
mString = rhs.mString;
mNumber = rhs.mNumber;
return *this;    
}