🚀 go-pugleaf

In article <1993Jan21.004406.6508@informix.com>  I asked for help
regarding why, after finally getting a clean compile of gcc-2.3.3 the
compiler was unable to automatically find <iostream.h>; I was forced
to supply the directory in the -I option to g++.  When I did this the
compile completed the linker (or more accurately, collect) complained 
it was unable to find libg++.a (library for -lg++).  I got back some
important answers:

Mr. DM and AG (names witheld to protect their mailboxes ;) both replied
that I had needed to supply a --prefix parameter to the configure
command for both gcc and libg++.  Furthermore, the target directory
must be the same for both configure commands.

Unfortunately, this is documented only in the libg++ README, not in
the gcc readme (I just ran a grep on it; it isn't there!) and I really
had used the --prefix in the configure on gcc.  SHort of going through
all that building again (remembering to drop the -g from all Makefiles
and uncommenting/commenting for various models! UGH!)  what can I do
to make use of everything where it is?

Mr. JO to the partial rescue:  Here is his reply:

>I set up libg++ on decstation 5000/240 running Ultrix 4.?
>To search the various files the following env var are needed (for me)
>COMPILER_PATH (sound ok for you)
>LIBRARY_PATH  ( I think you need this )
>CPLUS_INCLUDE_PATH ( for includes )

Well, I set up the CPLUS_INCLUDE_PATH to reference where I had put
the include directory: /usr/gnu/lib/g++-include .. This helped it find
the <iostream.h> without my supplying the -I switch to g++.  However
the LIBRARY_PATH did not help the linker (or collect) find libg++.a,
no matter where I aimed it.  BTW, the directory gcc-lib is under
/usr/local/lib.

Thanks to all who sent me the help so far.  I'm almost there with only
one screw-up along the way.

C'mon Netters, please help hack my way around that screw-up!  As
before, please reply be e-mail.

Thanks again.

		-- Jake Salomon
		jacob@informix.com
-- 
----------------Obligatory smart-$$$ remark:---------------------
| There's two kinds of people: Those who categorize people into |
| two groups and those who don't.   (Barth's Aging proverb.)    |
-----------------------------------------------jacob@informix.com

I've recently been trying to get to grips with c++. I wrote the following
small programme to implement a list template. However, it does not behave as
I would have expected. If I define a list of chars or ints in main then all is
ok. But defining the list to be of type char* does not work. If I insert a
string item by typing 
   i aaa
then insert another string by typing
   i bbb
then type 
   d
to display the contents of the list, it prints out
   bbb bbb
If I then type
   s ccc
and then
   d
then what is printed out is 
   ccc ccc ccc
It seems that by reading in a string to the local char array item in main
causes the value of each element in list to be changed to the value of the
newly read in string. Could someone please put me out of my misery explain
what is going on.

Thanks in advance.
Mike Palmer.

PS. I am using gcc version 2.2.2

//////////////////////////////////////////////////////////////////////////////
// List template definition
//////////////////////////////////////////////////////////////////////////////
#include <assert.h>
#include <iostream.h>

enum Boolean { false = 0, true = 1 };
template <class Type> class Item;

template <class Type> 
class List {
   public:
      List() { firstItem = 0; }
      ~List() {}
      void insert(Type);
      void display();
   private:
      Item<Type> *firstItem;
};

template <class Type> 
class Item {
   friend class List<Type>;
   private:
      Item(Type value) { val = value; next = 0; }
      Type val;
      Item *next;
};

template <class Type> 
void List<Type>::insert(Type val) {
   Item<Type> *pt = new Item<Type>(val);
   assert( pt != 0 );   // catch free store exhaustion
   pt->next = firstItem;
   firstItem = pt;
}


template <class Type> 
void List<Type>::display() {
   for ( Item<Type> *pt = firstItem; pt; pt = pt->next )
      cout << pt->val << " ";
   cout << endl;
}

//////////////////////////////////////////////////////////////////////////////
// Define and test a list of strings.
////////////////////////////////////////////////////////////////////////////// 
main () { 
   typedef char *Type;	
   List<Type> *list = new List<Type>; // create a list of strings
   char ch; 		// select test operation
   char  item[10];	// input string buffer
   while ( cin >> ch )
      switch(ch) {
	 case 'q':
	    return 1;
	 case 's':
            cin >> item;
            cout << item << '\n';
	    break;
         case 'i':
            cin >> item;
            list->insert(item);
            break;
         case 'd':
            list->display();
            break;
      }
}

In <7684@sersun1.essex.ac.uk> palmm@csc2.essex.ac.uk (Palmer M J) writes:

	>> dicussion about linked list implementation deleted <<

The problem you have is in the concept string. You expect the behaviour
of a decent string, and you use char *.

You get the expected behaviour by using the String type defined by
#include <String.h>. Just change your typedef line to:
   typedef String Type;
instead of
   typedef char * Type;

Klamer
--
Klamer Schutte			Tel: +31-53-892778	Fax: +31-53-340045
Faculty of electrical engineering -- University of Twente, The Netherlands
preferred: klamer@mi.el.utwente.nl     SMTP: klamer@utelmi01.el.utwente.nl