Syntax questions

[Esteban]

I hope my question is not too stupid, but I could not find any help googling it, nor reading the website.
1. In c++ the prototype of a function returning a pointer is somehing like
*pVariable function(argType arg,...)
But i keep reading codes which contains
&pVariable funcion(argType arg,...)
What does is mean ?

2. I also don't understand this prototype syntax:
Variable &function(...)

Is it the same than previously mentionned ?

3. Same thing for some variable declarations, what is exactly this syntax?
int& i;
is is the same like int* i ?

Any help greatly appreciated

[MrHutch]

& is a reference operator.
* is a dereference operator.

A fairly simple explanation is that & will return you the memory address of an object. * will return what the object is pointing to.

Little more complex than that in cases, but that's the general swing of it.

[Esteban]

I got that in the case of pointers, with addresses and values.

But here that's not used to declare a reference to a function or a variable, or ? Those prototypes are the declarations of the functions themselves. And To declare a reference to a variable I do something like int *i=0;
Then what is:
int& i;
ClassA& = ClassA(...);
??

[Moschops]

And To declare a reference to a variable I do something like int *i=0;

No, that creates a pointer.


To create a reference:

int a;  // make an int
int& z = a; // z is a reference to a 

[Esteban]

Yeah, bad vocabulary.

But then does something like this say that the function will return a reference ?

Variable var &function(int a,int b){
...
}

[zb0S216C]

Yes, it does. However, that's an invalid function definition. What you're doing there is mixing an object declaration within a function definition. Remove var from it, then it becomes a valid function definition. Also, make sure you don't return a reference to a local object. Bad things happen.

_Wazzak

[Esteban]

Okay, thank you for the answers. So those 3 are exactly the same :

int& function(int a,int b)
int &function(int a,int b)
int* function(int a,int b)

and those 4 too :
int *i;
int* i;
int &i;
int& i;

That's it ?

I'm a bit confused wih that. For an example here is a sample of code I read:

template<typename T>
const T &limit(const T &val, const T &minimum, const T &maximum)
{ 
	if(val < minimum) return minimum;
	return val > maximum ? maximum : val;
}

The function is returning some variable of T type and not *T, right ?

[zb0S216C]

Esteban wrote:

int& function(int a,int b)
int &function(int a,int b)
int* function(int a,int b)

The 1^st & 2^nd are the same, but the 3^rd is different. Pointers are not the same as references.

Esteban wrote:

int *i;
int* i;
int &i;
int& i;

Again, the 1^st & 2^nd are the same, and the 3^rd & 4^th are the same. However, the 1^st & 2^nd are not the same as the 3^rd & 4^th.

Edit:

It doesn't matter where the asterisk (*) or ampersand (&) appears between the type and identifier, so long as it's there. For example, these are valid (but annoying) declarations:

/* Annoying reference declaration: */
const int                            &                        Symbolic_Value( 10 );
/* Annoying pointer declaration:  */
int               *   Pointer( 0x0 );

Esteban wrote:

I'm a bit confused wih that. For an example here is a sample of code I read:

template<typename T>
const T &limit(const T &val, const T &minimum, const T &maximum)
{ 
	if(val < minimum) return minimum;
	return val > maximum ? maximum : val;
}

The function is returning some variable of T type and not *T, right ?

That function will return a reference to constant data, and not a pointer.

_Wazzak

[Esteban]

Okay, thank you very much, that makes it a lot clearer for me !