What's up with iostream.h, is it obsolete?

linuxlah · 02-03-2003, 08:34 PM

when I woke up in the morning I usually will try to compile my hello world program( nice intro huh?). In my RH8 machine, it compile but it gave me backward warning like this..

/usr/include/c++/3.2/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header. Please consider using one of the 32 headers found in section 17.4.1.2 of the C++ standard. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <sstream> instead of the deprecated header <strstream.h>. To disable this warning use -Wno-deprecated.

It seems like iostream.h is obsolete. So I tried to remove the .h like the warning suggested, but it didn't work. My code can't recognize my "cout" when I remove the .h in my #include <iostream.h>.....

moeminhtun · 02-04-2003, 12:46 AM

Whenever you use the new standard C++ library without ".h", you have to put the "std::" infront throughout your code.
For example,

#include <iostream>

main() {
std::cout << "hello\n";
return 0;
}

If you don't want to put "std::" throughout the program, you can write the line "using namespace std;" just below your header file declaration.
For example,

#include <iostream>
using namespace std;

main() {
cout << "hello\n";
return 0;
}

linuxlah · 02-04-2003, 01:26 AM

cool. It seems like we need to localize the std in order to use the <iostream> only. Thanks.

GtkUser · 02-04-2003, 03:13 AM

That's actually the good thing about gcc/g++ is that it recognizes changes in Standard C++. The .h extension is deprecated.

sathyan · 02-04-2003, 06:29 AM

I was fumbling with the same problem and when I poked around I found the old compiler named as g++296 sitting there which does not give the above warning. Any ways, now I know why the code is not working for the new compiler