operator << and >>

[iLL]

Okay, I’m just a little confused on exactly what the system is doing when I say:

#include <iostream>
 
class test
{
private:
    int i;
public:
    friend std::ostream& operator<< (std::ostream& o, test t);
    test()
    {
        i = 10;
    }
};
std::ostream& operator<< (std::ostream& o, test t)
{
    return o << t.i <<std::endl;
}
 
int main()
{
    test testing;
    std::cout << testing;
    return 0;
}
 

I get that I’m overloading an operator, but whose operator am I overloading.

It’s not overloading anything in test, and it’s not overloading anything in any other class because it’s not member of any class. It’s just a friend of a class.

Is it overloading cout or some other buffer? If so, then what? how the heck? I dont know??????????? ?????????????

[DeMan]

your overloading << (or >>)

[DeMan]

<< and >> do some interesting bitwise operations.

Try

int x=1<<5;
printf("What happens here %d", x);
 
int y=x>>4;
printf("or here %d",y);
 

Can you see what's going on? See if you can figure it out, if you can't post back.

[iLL]

<< and >> do some interesting bitwise operations.

Try

int x=1<<5;
printf("What happens here %d", x);
 
int y=x>>4;
printf("or here %d",y);
 

Can you see what's going on? See if you can figure it out, if you can't post back.

It moves bits to the left and right. Very cool (!), didn’t know you could do that.

your overloading << (or >>)

I know I am. But for what class? It isn’t referring to any classes.

[thefarmer]

It moves bits to the left and right. Very cool (!), didn’t know you could do that.



I know I am. But for what class? It isn’t referring to any classes.

hi there,

your overloading this part, you should not type this in this manner

by the way "return o" is this "0" or letter "o", that's also a mistake
delete << t.i <<std::endl; put that on the other statement

{
return o << t.i <<std::endl;
}

ok,

regards,

[iLL]

hi there,

your overloading this part, you should not type this in this manner

by the way "return o" is this "0" or letter "o", that's also a mistake
delete << t.i <<std::endl; put that on the other statement

{
return o << t.i <<std::endl;
}

ok,

regards,

Noooo……..

The thing is it SHOULD be written in that manner. If you took the time to compile it, it works flawlessly.

The “return o” isn’t returning the letter ‘o’ or the number zero (0); o is an object of an ostream buffer. It’s a variable.

And I’m not sure what you mean by the “other statement”



I found in one of my textbooks that I am overloading ostream. However, it doesn’t follow the C++ norm, and I’m still having a hard time wrapping my mind around it. I don’t like doing something for the simple fact of knowing that is how it is done. I like to know what is going on.

[Ganon11]

I believe that you are overloading the insertion operator (<<) in the ostream class (specifically, std::cout) - but only when inserting objects of class test. In other words, if you have the statement

std::cout << 24 << " is a cool number in my class test: " << myTestClassObject << std::endl;

std::cout will work normally as it prints the integer 24 and the string. But when it comes to myTestClassObje ct, it detects that you have overloaded the << operator, so it instead follows your directions for printing. once done, cout moves onto std::endl, which it knows how to process.