Programming Forums > Application Development > C++

lucifer · Dec 19th, 2007, 8:36 AM

Is
cout.operator<<("Factorial of :");
same as
cout << "Factorial of:" ;
I have searched google and checked books and all of them say it is but when i run the same code the former code gives me the address of the string.

Narue · Dec 19th, 2007, 1:08 PM

>I have searched google and checked books and all of them say it is
They're wrong. cout<<"blah" is a non-member function that's defined to work with C-style strings:

 cpp Syntax (Toggle Plain Text) 
template <typename T, typename Traits>
basic_ostream<T, Traits>& operator<< (
  basic_ostream<T, Traits>& out, const char *s )
{
  // Magic
}
template <typename T, typename Traits>
basic_ostream<T, Traits>& operator<< (
  basic_ostream<T, Traits>& out, const char *s )
{
  // Magic
}

There's no equivalent member function in basic_ostream. The closest you'll get is an overloaded operator that takes a pointer to void:

 cpp Syntax (Toggle Plain Text) 
T& operator<< ( const void *p )
{
  // Magic
}
T& operator<< ( const void *p )
{
  // Magic
}

That's why the member function gives you a number (it treats the string as a pointer) and the non-member function works like you'd expect.

Dec 19th, 2007, 8:36 AM	#1
lucifer Programmer Join Date: Oct 2005 Posts: 84 Rep Power: 3	Cout Problem Is `cout.operator<<("Factorial of :");` same as `cout << "Factorial of:" ;` I have searched google and checked books and all of them say it is but when i run the same code the former code gives me the address of the string. __________________ "You're good... but me, I'm magic"

Dec 19th, 2007, 1:08 PM	#2
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 3	Re: Cout Problem >I have searched google and checked books and all of them say it is They're wrong. cout<<"blah" is a non-member function that's defined to work with C-style strings: cpp Syntax (Toggle Plain Text) template <typename T, typename Traits> basic_ostream<T, Traits>& operator<< ( basic_ostream<T, Traits>& out, const char s ) { // Magic } template <typename T, typename Traits> basic_ostream<T, Traits>& operator<< ( basic_ostream<T, Traits>& out, const char s ) { // Magic } There's no equivalent member function in basic_ostream. The closest you'll get is an overloaded operator that takes a pointer to void: cpp Syntax (Toggle Plain Text) T& operator<< ( const void p ) { // Magic } T& operator<< ( const void p ) { // Magic } That's why the member function gives you a number (it treats the string as a pointer) and the non-member function works like you'd expect. __________________ Even if the voices aren't real, they have some pretty good ideas.

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Programming Forums > Application Development > C++

Cout Problem