Why operator>> of istream class have return type of reference?

[gkfkagkfka12]

Sorry for my bad English.

I'm stdying the overloading of "<<" operator.

so I must use istream/ostream class to override.

But I don't understand why these classes operator>>/<< have return type of reference.

and parameter type of reference.

Can u explain for me?

[LilXeno]

i'm not too sure.

It normally goes

cout << stuff << endl;

cin >> stuff >> endl;

(I don't know what else to say. That's all I know about C++ kinda sorta.)

I hope that helped at least a little bit!
If not, sorry for wasting your time

[Chervil]

Parameter type of reference:

a) When passing by value, the parameter receives a copy. But istream/ostream are not copyable, so it cannot be passed by value. So it is passed by reference.
b) the istream / ostream is modified when reading/writing, again this means it must be passed by reference.

Return type of reference to istream/ostream:

This allows the >> and << operators to be used in the familiar ways we are used to for other types, such as chaining several different items in the same statement, such as

    cout << "values are " << a << b << c << endl; 

If the reference was not returned, then only a single item could be handled at a time. cout << a;

It also allows testing the outcome in the usual ways, such as

    while (infile >> a >> b >> c)
    {
         // do something with values read from file 

Here, the while or if tests the status of the stream after the input operation, and depends on the returned reference.