g++ versus gcc

g++ versus gcc

[William Trenker]

(This has probably been asked a million times, but I did search the lists 
and came up with only sketchy information.)

Today I upgraded my Linux 2.4.19 system from gcc 2.95.3 to gcc 3.2.  I used 
this test program:

#include <iostream>
struct test {
    test(char* m) : msg(m) {};
    char* msg;
};
main()
{
    test* ptest = new test("Hello World");
    cout << ptest->msg << endl;
};

To build this I used the time-honored:  "gcc -o test test.cpp".

The build failed with the compiler complaining that "cout" and "endl" 
weren't declared, and the linker grumbled that it couldn't resolve 
references to "new", "delete", "cout", "basic_ostream" and other standard 
objects.

A search on the mailing lists, and with Google, pointed out that I have to 
explicitly decare namespace "std" -- gcc no longer defaults to "std".  
Further searching suggested that I should be using "g++", not "gcc".  Doing 
both these things resulted in my little test program building and running 
without error.

So now, it seems, we need to change all our makefiles, or the relevant 
environment variables, to use "g++" instead of "gcc" for building c++ files.

I would appreciate confirmation that the use of "g++" has officially 
replaced the use of "gcc" for c++ builds.

Thanks very much,
Bill Trenker
Kelowna BC Canada


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Re: g++ versus gcc

[LLeweLLyn Reese]

"William Trenker" <wtrenker@hotmail.com> writes:

> (This has probably been asked a million times, but I did search the
> lists and came up with only sketchy information.)
> 
> Today I upgraded my Linux 2.4.19 system from gcc 2.95.3 to gcc 3.2.  I
> used this test program:
> 
> #include <iostream>
> struct test {
>     test(char* m) : msg(m) {};
>     char* msg;
> };
> main()
> {
>     test* ptest = new test("Hello World");
>     cout << ptest->msg << endl;
> };
> 
> To build this I used the time-honored:  "gcc -o test test.cpp".
> 
> The build failed with the compiler complaining that "cout" and "endl"
> weren't declared, and the linker grumbled that it couldn't resolve
> references to "new", "delete", "cout", "basic_ostream" and other
> standard objects.
> 
> A search on the mailing lists, and with Google, pointed out that I
> have to explicitly decare namespace "std" -- gcc no longer defaults to
> "std".  Further searching suggested that I should be using "g++", not
> "gcc".  Doing both these things resulted in my little test program
> building and running without error.
> 
> So now, it seems, we need to change all our makefiles, or the relevant
> environment variables, to use "g++" instead of "gcc" for building c++
> files.

No. Change them to use a variable - $(CXX) . Maintainable makefiles do
    this anyway.

> 
> I would appreciate confirmation that the use of "g++" has officially
> replaced the use of "gcc" for c++ builds.

I'm not an official gcc rep, but even with 2.95.3 I was never able to
    get significant C++ prgrams to link without using 'g++'.

However I can't find explicit support for this in their
    documentation. Spooky.

[snip]

Re: g++ versus gcc

[Ben Elliston]

>>>>> "William" == William Trenker <wtrenker@hotmail.com> writes:

  William> So now, it seems, we need to change all our makefiles, or the relevant
  William> environment variables, to use "g++" instead of "gcc" for building c++
  William> files.

  William> I would appreciate confirmation that the use of "g++" has
  William> officially replaced the use of "gcc" for c++ builds.

This has been the case for a long time, if not forever.  g++ passes a
number of C++-specific options to the compiler and the linker that are
required for correct C++ compilation.

As for the issues with std::cout, G++ is always gravitating closer to
the C++ standard.  Previously, it allowed non-conforming C++ programs
to build -- now it's time to fix the code.

  William> Kelowna BC Canada

Lucky you. :-)

Ben