OSDev.org

Posted: **Sat Aug 30, 2014 7:39 am**

It may be a stupid question but I'm not able to find the answer- why there is no reference variable in C like C++??

Like in C++:
int a;
int& b = a;

I think answer might be some approved C standard but i'm not sure, so what do you think ??

Posted: **Sat Aug 30, 2014 7:52 am**

Because references are basically pointer sugar, and C was specifically designed to have explicit pointer operations and as little sugar as possible.

Posted: **Sat Aug 30, 2014 11:14 am**

@Icee: Thank you very much.

Posted: **Sat Aug 30, 2014 9:35 pm**

You could probably get away with this though

Code: Select all

int *a = ({ static int _a = 0; &_a });

It's part of a gcc function expression extension, so it definitely won't work in most compilers (if at all)

Posted: **Sat Aug 30, 2014 10:47 pm**

@DaemonR: Thank you.
But this will again involve pointers(which are apparent to programmers) and will have their own memory address whereas in C++ reference variables variable and its alias share the same memory address(Correct me if I'm wrong).

Posted: **Sat Aug 30, 2014 11:03 pm**

dansmahajan wrote:@DaemonR: Thank you.
But this will again involve pointers(which are apparent to programmers) and will have their own memory address whereas in C++ reference variables variable and its alias share the same memory address(Correct me if I'm wrong).

This in C++

Code: Select all

int &a;
a += 1;

Is roughly the same as this in C:

Code: Select all

int _a, *a = &_a;
*a += 1;

It's just syntactical sugar.

Posted: **Sun Aug 31, 2014 2:15 am**

Hi,

DaemonR wrote:This in C++
Code: Select all
int &a;
a += 1;
Is roughly the same as this in C:
Code: Select all
int _a, *a = &_a;
*a += 1;
It's just syntactical sugar.

Yes; and this in C++:

Code: Select all

void foo(int &var) {
    var++;
}

Is roughly the same as this in C:

Code: Select all

void foo(int *var) {
    (*var)++;
}

Except for the fact that in C the caller would do "foo(&bar);" (which makes it obvious that bar may be modified), and in C++ the caller does "foo(bar);" where it looks like the variable is passed by value and safe from modification when it's not.

This is what makes it "syntactical sugar poured into your gas tank".

Cheers,

Brendan

Posted: **Sun Aug 31, 2014 3:10 am**

Brendan wrote:Except for the fact that in C the caller would do "foo(&bar);" (which makes it obvious that bar may be modified), and in C++ the caller does "foo(bar);" where it looks like the variable is passed by value and safe from modification when it's not.

Agree, therefore I still pass by pointer when the value would be modified, although this means adding an extra a null check.

Pass by reference is still useful when it's const:

Code: Select all

int foo(const MyClass& c) {
    return c.get_foo();
}

OSDev.org

alias/reference variable in C

alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C

Re: alias/reference variable in C