LinuxQuestions.org - C++ iostream - getting "deprecated header" error

- Programming (https://www.linuxquestions.org/questions/programming-9/)

- - C++ iostream - getting "deprecated header" error (https://www.linuxquestions.org/questions/programming-9/c-iostream-getting-deprecated-header-error-235980/)

C++ iostream - getting "deprecated header" error

I have a simple program I am using to explore typedef and structs more:

Code:

// /usr/include/c++/3.3/backward/iostream.h



#include <iostream.h>



typedef struct test_struct{

    int a;

    long b;

    char *c;

} *p_test;



int main(void){



    test_struct t;

    p_test p;

    

    p = &t;



    cout << "Size Of Struct: " << sizeof(test_struct) << " bytes" << std::endl;

    

    cout << "Address Of Struct: " << &t << std::endl;

    

    cout << "Size Of a: " << sizeof(t.a) << " bytes" << std::endl;

    

    cout << "Address Of a: " << &t.a << std::endl;    

    

    cout << "Size Of p: " << sizeof(p) << " bytes" << std::endl;

    

    cout << "Address Of p: " << &p << std::endl;    

    

    cout << "Contents Of p: " << p << std::endl;    

    

}

I compile with

Quote:

g++ -o hello -g hello.c

Then I get this warning:

/usr/include/c++/3.3/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.

I did a

Code:

find / -name iostream.h

and the only path that came up was /usr/include/c++/3.3/backward/iostream.h which is the very iostream that I linked to. Where is the "correct" iostream? Is it in some package? How does this work? Thanks.

Just do #include <iostream> instead of #include <iostream.h>. It's not a matter of using the incorrect header, it's a matter of including the header correctly :)

Futhermore add

using namespace std;

like :

#include <iostream>
#include <list>

using namespace std;

int main ()
{
....
}

Thanks for the response. Could someone explain 'why' the declaration is incorrect and 'how' Linux utilizies these libraries. Also, is the iostream I found using the find function the one being used in the program? Where are Linux libraries usually stored. I am more interested in learning what is happening here rather than the syntax, although I appreciate the help on that too! Thanks.