Linuxhelp > C++ Compilation

beni

Apr 20 2004, 01:13 AM

I've RHL 9 (kernel 2.4.20) and the standard gcc/g++ that ships with the distro. I included the iostream header as <iostream.h>, and got an error msg from g++ about some deprecation. Then I changed the header file to <iostream>. Then the compiler fasils to ercognise the cout function. Now can please anyone tell me how to compile a C++ program using g++?

michaelk

Apr 20 2004, 03:44 PM

should be:
#include <iostream>
using namespace std;

If I remember it was just a warning not an error if you used iostream.h instead of iostream.

Hemant

Apr 21 2004, 07:23 AM

Yeah...exactly..new ISO c++ standards suggest following way of including header files..
#include <iostream>

thus the old style is deprecated..you can use it..but it means that support will be removed from future versions of g++.
now the second line...
using namespace std;
is required because...keywords like..cout,endl,cin are not in the current namespace...thus compiler will not recognise these keywords..unless you specify which namespace to use.
thus you can have two styles of coding...

CODE

#include <iostream>
using namespace std;
int main()
{
cout<<"Hello World"<<endl;
return 0;
}

or the other style could be like..this..

CODE

#include <iostream>
int main()
{
std::cout<<"Hello World"<<std::endl;
return 0;
}

or another style code could be..

CODE

#include <iostream>
using namespace std::cout;
using namespace std::cin;
using namespace std::endl;
int main()
{
cout<<"Hello World"<<endl;
return 0;
}

The idea behind this style is...you don't use the entire namespace..but only these three keywords..will belong to std
namespace.

beni

Apr 22 2004, 02:41 AM

Thnx guys. The help is really appreciated

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