blocks|key|1425203|text|内部类是定义它的类的朋友。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425204|所以，可以；类型为Outer::Inner的对象可以访问类型为Outer的对象的成员变量var。|offset|length|style|CODE|1425205|与Java不同的是，Outer::Inner类型的对象和父类的对象之间没有相关性。您必须手动创建父子关系。|1425206|#include+<string>
#include+<iostream>

class+Outer
{
++++class+Inner
++++{
++++++++public:
++++++++++++Inner(Outer&+x):+parent(x)+{}
++++++++++++void+func()
++++++++++++{
++++++++++++++++std::string+a+=+"myconst1";
++++++++++++++++std::cout+<<+parent.var+<<+std::endl;

++++++++++++++++if+(a+==+MYCONST)
++++++++++++++++{+++std::cout+<<+"string+same"+<<+std::endl;
++++++++++++++++}
++++++++++++++++else
++++++++++++++++{+++std::cout+<<+"string+not+same"+<<+std::endl;
++++++++++++++++}
++++++++++++}
++++++++private:
++++++++++++Outer&++parent;
++++};

++++public:
++++++++Outer()
++++++++++++:i(*this)
++++++++++++,var(4)
++++++++{}
++++++++Outer(Outer&+other)
++++++++++++:i(other)
++++++++++++,var(22)
++++++++{}
++++++++void+func()
++++++++{
++++++++++++i.func();
++++++++}
++++private:
++++++++static+const+char*+const+MYCONST;
++++++++Inner+i;
++++++++int+var;
};

const+char*+const+Outer::MYCONST+=+"myconst";

int+main()
{

++++Outer+++++++++++o1;
++++Outer+++++++++++o2(o1);
++++o1.func();
++++o2.func();
}|code-block|syntax|javascript|1425207|entityMap^0|0|9|C|V|5|18|3|0|A|C|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]|$D|U|E|V|F|G]|$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@$D|Z|E|10|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|P|$]]

An inner class is a friend of the class it is defined within. 
So, yes; an object of type <code>Outer::Inner</code> can access the member variable <code>var</code> of an object of type <code>Outer</code>.

Unlike Java though, there is no correlation between an object of type <code>Outer::Inner</code> and an object of the parent class. You have to make the parent child relationship manually.

<pre><code>#include &lt;string&gt;
#include &lt;iostream&gt;

class Outer
{
 class Inner
 {
 public:
 Inner(Outer&amp; x): parent(x) {}
 void func()
 {
 std::string a = "myconst1";
 std::cout &lt;&lt; parent.var &lt;&lt; std::endl;

 if (a == MYCONST)
 { std::cout &lt;&lt; "string same" &lt;&lt; std::endl;
 }
 else
 { std::cout &lt;&lt; "string not same" &lt;&lt; std::endl;
 }
 }
 private:
 Outer&amp; parent;
 };

 public:
 Outer()
 :i(*this)
 ,var(4)
 {}
 Outer(Outer&amp; other)
 :i(other)
 ,var(22)
 {}
 void func()
 {
 i.func();
 }
 private:
 static const char* const MYCONST;
 Inner i;
 int var;
};

const char* const Outer::MYCONST = "myconst";

int main()
{

 Outer o1;
 Outer o2(o1);
 o1.func();
 o2.func();
}
</code></pre>

blocks|key|1425289|text|内部类可以访问外部类的所有成员，但它没有对父类实例的隐式引用(与Java的一些奇怪之处不同)。因此，如果将对外部类的引用传递给内部类，则它可以引用外部类实例中的任何内容。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425290|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

An inner class has access to all members of the outer class, but it does not have an implicit reference to a parent class instance (unlike some weirdness with Java). So if you pass a reference to the outer class to the inner class, it can reference anything in the outer class instance.

blocks|key|1425395|text|var不是内部类的成员。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1425396|要访问var，应该使用指向外部类实例的指针或引用。例如，如果内部类是外部类的朋友，则pOuter->var将起作用，或者，如果严格遵循C%2B%2B标准，则var是公共的。|1425397|一些编译器将内部类视为外部类的朋友，但有些则可能不是。请参阅this+document+for+IBM+compiler|offset|length|1425398|“在另一个类的作用域中声明嵌套类。嵌套类的名称是其封闭类的局部名称。除非您使用显式指针、引用或对象名，否则嵌套类中的声明只能使用可见的结构，包括类型名称、静态成员、封闭类的枚举器和全局变量。|1425399|嵌套类的成员函数遵循常规访问规则，并且对其封闭类的成员没有特殊访问权限。封闭类的成员函数对嵌套类的成员没有特殊访问权限。“|1425400|entityMap|0|LINK|mutability|MUTABLE|url|http://publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/index.jsp?topic=/com.ibm.xlcpp8l.doc/language/ref/cplr061.htm^0|0|0|U|U|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@$F|W|G|X|1|Y]]|A|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|10|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]]]

var is not a member of inner class.

To access var, a pointer or reference to an outer class instance should be used. e.g. pOuter->var will work if the inner class is a friend of outer, or, var is public, if one follows C++ standard strictly.

Some compilers treat inner classes as the friend of the outer, but some may not. See <a href="http://publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/index.jsp?topic=/com.ibm.xlcpp8l.doc/language/ref/cplr061.htm" rel="nofollow">this document for IBM compiler</a>:

"A nested class is declared within the scope of another class. The name of a nested class is local to its enclosing class. Unless you use explicit pointers, references, or object names, declarations in a nested class can only use visible constructs, including type names, static members, and enumerators from the enclosing class and global variables.

Member functions of a nested class follow regular access rules and have no special access privileges to members of their enclosing classes. Member functions of the enclosing class have no special access to members of a nested class."

<pre><code>class Outer {

 class Inner {
 public:
 Inner() {}
 void func() ;
 };

private:
 static const char* const MYCONST;
 int var;
};

void Outer::Inner::func() {
 var = 1;
}

const char* const Outer::MYCONST = "myconst";
</code></pre>

This errors out when I compile with class Outer::Inner' has no member named `var'

Can inner classes access private variables?

编译器

Java

class Outer {    class Inner {    public:        Inner() {}        void func() ;    };private:    static const char* const MYCONST;    int var;};void Outer::Inn...

问内部类可以访问私有变量吗？
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