reference 变量的几个问题

问题:

当你声明一个pointer时，系统会给这个变量分配多少内存？

   根据OS的位数，32位返回4个字节，64位8个字节

当你声明一个reference变量时，系统会给这个变量分配多少内存？

  不分配空间。reference变量和所关联的变量是同一个变量。

   int x;

   int &ref=x;
   cout<<endl<<&x;        //address of ‘x’
   cout<<endl<<&ref;     //address of ‘ref’ 

  Both addresses will be the same (which is whyworking on ‘x’ is the same as working on ‘ref’).

Compiler 会在编译的时候用x来代替ref.

 

当一个函数用Pass by reference 的时候，compiler是如何实现的？

   As forpass-by-reference, if a language has pointers, pass by reference can be done bypassing pointers by value. The compiler can just have a preprocessing stepwhere it "eliminates" pass by reference by making the followingtranslation:

• For every function parameter that is pass by reference, it changes it to a pointer to that type passed by value (e.g. void func(int &foo) -> void func(int *foo))
• For every use of that pass-by-reference parameter inside that function, change it to an explicit pointer dereference (e.g. foo -> *foo) (with the exception that if it is passed by reference again, don't dereference it)
• Every time that function is called, whatever is passed to the pass-by-reference variable, take the address of it explicitly (e.g. func(bar) -> func(&bar))