-> Operator

**nathanpc** · 06-15-2010

Hello,
I know that this could seen as an extreme beginner question, but I haven't learned this on the book "C Programming Language", as everyone is here to learn and to help, then I think that people should answer nice and very helpful. Anyway, I don't know if that is an operator, but I want to know what is the use of it in a source, as on this example:

Code:

something->someFunction();

Also, I want to know in which cases it's most used, what types of object I can use on the right and on the left side of the expression.

Remember to be a gently person when answering(because I think this question is too noob that people can be a bit ignorant when answering), also that everyone is here to learn and be respected.

Best Regards,
Nathan Paulino Campos

**Prelude** · 06-15-2010

as everyone is here to learn and to help, then I think that people should answer nice and very helpful

Remember to be a gently person when answering(because I think this question is too noob that people can be a bit ignorant when answering), also that everyone is here to learn and be respected.

This alone makes me want to bully you...

what is the use of it in a source, as on this example

It's a convenience operator for accessing a structure member through a pointer to a structure:

Code:

struct foo {
  int x;
} *p;

Assuming the pointer is initialized, these two statements are equivalent:

Code:

p->x = 123;
(*p).x = 123;

**nathanpc** · 06-15-2010

Thanks very much, now I've understood.

I've liked the second one because it's a little bit object-oriented.

**LordPc** · 06-15-2010

in a bad way though

should be using getters and setters for that kind of stuff

**zacs7** · 06-15-2010

Originally Posted by LordPc

in a bad way though

should be using getters and setters for that kind of stuff

That doesn't make sense, you'll still have to dereference the pointer.

i.e.

Code:

const char * getName(struct foo * f)
{
   return f->name;
}

I don't see how "getters" nor "setters" let you avoid "->".

**LordPc** · 06-15-2010

he said he prefers the second way cause its like oo.

Code:

   p->x = 123;
   (*p).x = 123;

i took this as meaning that he likes dot notation. except, in oo, you dont refer to variables through dots, you use getters and setters. so that kind of code should never pop up in oo which is why i said "in a bad way" cause it means he might be writing poor oo code...

**quzah** · 06-16-2010

That doesn't even make sense. You still have to write the getter/setter, so you still end up referring to the variables directly at some point. They don't write themselves you know.

Quzah.

**LordPc** · 06-16-2010

Originally Posted by quzah

That doesn't even make sense. You still have to write the getter/setter, so you still end up referring to the variables directly at some point. They don't write themselves you know.

Quzah.

well ofcourse you do, in the getter and setter. nowhere else though, thats what the getter/setter is for

**quzah** · 06-16-2010

You're still not gaining anything.

Code:

x = foo.bar;

Isn't any harder to write than:

Code:

x = getbar( foo );

Quzah.

**LordPc** · 06-16-2010

im talking about oo programming. im not sure you are...

**whiteflags** · 06-16-2010

He's trying to tell you that there is no perceived OOPness about the dot operator. When we consider what the dot operator does, it would have been just as acceptable to not have an operator. It's inclusion was merely a syntax decision.

For example, any number of std::string's functions would be close to the same. (Forget that this is the C board for a minute)

std::string foo = "Life, the universe, and everything.";
std::string::size_type len = length (foo);
std::string::size_type pos = find (foo , "the");

Only that you have to pass a reference to the accessed object.

The arrow operator is just a construct for member access from pointers; it's still the same example.

len = length (*bar);
pos = find (*bar, "the");

We probably wouldn't have an extra operator if it were like this.

**Bayint Naung** · 06-17-2010

getter and setter are useful if you use them right.

Code:

const char * getName(struct foo * f)
{
  if( f->name == NULL ) 
     return "foobar";              // our policy
  return f->name;

}

getters and setters

**whiteflags** · 06-17-2010

No one really argued that though ... somehow we lost track of what OP was really asking and I still think LordPc was defending the sweetness of some syntactic sugar.

**claudiu** · 06-17-2010

Originally Posted by LordPc

im talking about oo programming. im not sure you are...

C is a OO language..... NOT!

Did you catch the Borat joke there?

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