TITLE: stl, stacks, and changing standards

(Newsgroups: comp.lang.c++.moderated, 13 May 97)

MOORE: "John I. Moore, Jr." <70672.1744@compuserve.com>

First, here are several good books about STL.

[Glass 1996]  Graham Glass and Brett Schuchert, The STL <Primer>,
   Prentice-Hall, 1996.

[Musser 1996]  David R. Musser and Atul Saini, STL Tutorial and Reference
   Guide:  C++ Programming with the Standard Template Library,
   Addison-Wesley, 1996.

[Nelson 1995]  Mark Nelson, C++Programmer's Guide to the Standard Template
   Library, IDG Books, 1995.

I would personally recommend [Musser] and [Nelson], but you should realize
that there have been some changes to the C++ standard and STL since these
books were published.  Look for new editions of these books in the next
year or so.

Second, there are trees in STL, but they are not obvious.  The
set class is implemented as a tree.  See if you can use the set class
for your work.

Third, your problem with stacks is a basic lack of understanding of
how stacks work in STL.  Essentially, stacks are not stand-alone classes
but are implemented as adaptors using one of the other container classes.
For example,

   stack<int> s;

is invalid, but

   stack< vector<int> > s;   // space required between two trailing ">"

is valid.  (Some implementations may require explicit mention of the
allocator in order to make this valid, but this is simply a temporary
deficiency in the compiler and should be corrected as the compiler
vendor moves toward standardization.


KUEHL: kuehl@uzwil.informatik.uni-konstanz.de (Dietmar Kuehl)


[ (Former) stack<int> s;
  (Latter) stack< vector<int> > s;    -adc ]

Note, that the latter is invalid under the definitions of the
forthcoming standard while the former is valid under these definitions!
Currently, the situation is reversed for some implementations... The
reason is a change of the adaptor classes. While eg. 'stack' is currently
defined as

  template <class Cont>
  class stack {...};

it will become

  template <class T, class Cont = vector<T> >
  class stack {...};

in a conforming implementation (see 23.2.3.3, lib.stack, of the Nov 96
DWP for a reference).