difference between Student& a, Student &a;

Question

I am confused about these terms.

Let suppose we have a class of Student then what will be the meaning of

class Student{
   public:
     Student(const Student& a){ ... }
     Student(const Student &a){ ... }
};

I want to ask the meaning of the following terms

Student& a;
Student &a;

These are used for copy constructors. The thing I know they are mostly used for deep and shallow copy constructor.

@UmarAsghar The argument named `a` is a [*reference*](https://en.wikipedia.org/wiki/Reference_%28C%2B%2B%29) to a `const Student`. That is, it refers to a `Student` object that is declared somewhere else, and cannot modify it. Another [tutorial](http://www.learncpp.com/cpp-tutorial/611-references/). — BoBTFish, Jan 14 '16 at 10:14
Isn't this one of those new, experimental C++0x features - one is an lvalue and the other an rvalue reference? — Kerrek SB, Jan 14 '16 at 10:22
@KerrekSB Upsettingly, that is guaranteed to work. As is `compl Student` for declaring a destructor. (Are you a bit bored this morning?) — BoBTFish, Jan 14 '16 at 10:29

score 1 · Answer 1 · edited May 23 '17 at 10:27

int   i   =   5;
^^^   ~       =
Type  Name  Value
(int) (i)    (5)


int&   ref   =  i;
^^^^^  ~~~      =
Type   Name   Value
(int&) (ref)   (i)


int  & ref   =  i;
^^^^^^ ~~~      =
Type   Name   Value
(int&) (ref)   (i)


int   &ref   =  i;
^^^^^^^~~~      =
 Type  Name   Value
(int&) (ref)   (i)

So basically these two:

Student& a;
Student &a;

are more or less the same thing.

As for what is the purpose of a copy constructor check out:

Did you really mean to initialize a reference to int with `nullptr`? I am surprised that compiles. — Martin Bonner supports Monica, Jan 14 '16 at 10:38

score 0 · Answer 2 · answered Jan 14 '16 at 10:42

When I was starting to learn C, I was confused about pointer syntax. char* c;, char * c; and char *c; seemed different to me and I was terrified with so many types in C.

But it turned out that you can put an asterisk anywhere in between the 'main' type name (e.g int, char, or even a pointer, etc) and the variable name. That means, all these declarations are the same.

This also applies to references in C++. Actually, it depends of the developer's coding style while the meaning doesn't change.

difference between Student& a, Student &a;

2 Answers2