Thread: Why do we need "this" in C++?

I understand "this" is for obtaining the object's address. And I understand that "this" is useful for assignment, for eg:

Code:

class A{
A operator =(const A& rhs){
if(this != &rhs){...}
}
};

But why do I see people writing code like this:

Code:

class A{
//..omit constructor...

void foo1(){
this->foo2(val_);
}
void foo2(int val){
val++;
}
private:
int val_;
}

Can't we just write

Code:

void foo1(){
foo2(val_);
}

Originally Posted by meili100

Can't we just write

Code:

void foo1(){
foo2(val_);
}

Yes we can.
Kurt

Originally Posted by ZuK

Yes we can.
Kurt

Then what's the goodness to use "this" pointer, except in the example I gave? At least you don't need to type the 6 extra letters and at the mean time keep your code clear./

Originally Posted by meili100

Then what's the goodness to use "this" pointer, except in the example I gave? At least you don't need to type the 6 extra letters and at the mean time keep your code clear./

What if an object needs to pass a pointer to itself to some other piece of code? "this" is the only way to get that pointer.

this points to the object itself.
So when you type function_name_here or variable_name_here, the compiler silently pushed this on the stack so that the data is modified in your own class.
If you try calling a class without a this, it will try to read/write from 0, thus causing a crash. This is used to identify where in memory the class lies.
Usually, you don't really need to use it in your class, but the compiler needs it.
But this can also be used to check in a copy constructor or such, to make sure you aren't copying yourself into yourself.

I don't think I've ever had to use this when calling a member function. Maybe some people just go a little this crazy?

Yep. It's not often very useful (except in rare cases, such as when you don't want the user to copy the same object into itself).
It has its uses, but not very often.

I usually don't, but when I use the Refractor, it lists everything w/o needing to do this->
It's so very useful! Love it!