Preface xvii
is contained in the text, not the code. The code complements the text, not the other
way around.
The code examples provide less parameter checking than is sound program-
ming practice for professional programmers. Some parameter checking and testing
for other constraints (such as whether a value is being removed from an empty con-
tainer) is included in the form of a call to Assert. Assert is a modified version
of the C library function assert. The inputs to Assert are a Boolean expres-
sion and a character string. If this expression evaluates to false, then the string
is printed and the program terminates immediately. This behavior is generally con-
sidered undesirable in real programs. CPP provides a good alternative mechanism
through exception handling. However, Assert provides a simpler mechanism for
indicating required conditions in a way that is both adequate for clarifying how a
data structure is meant to operate, and is easily modified into true exception han-
dling. See the Appendix for the implementation of Assert.
I make a distinction in the text between “C
++
implementations” and “pseu-
docode.” Code labeled as a C
++
implementation has actually been compiled and
tested on one or more C
++
compilers. Pseudocode examples often conform closely
to C
++
syntax, but typically contain one or more lines of higher-level description.
Pseudocode is used where I perceived a greater pedagogical advantage to a simpli-
fied, but less precise, description.
Exercises and Projects: Proper implementation and anaysis of data structures
cannot be learned simply by reading a book. You must practice by implementing
real programs, constantly comparing different techniques to see what really works
best in a given situation.
One of the most important aspects of a course in data structures is that it is
where students really learn to program using pointers and dynamic memory alloca-
tion, by implementing data structures such as linked lists and trees. Its also where
students truly learn recursion. In our curriculum, this is the first course where
students do significant design, because it often requires real data structures to mo-
tivate significant design exercises. Finally, the fundamental differences between
memory-based and disk-based data access cannot be appreciated without practical
programming experience. For all of these reasons, a data structures course cannot
succeed without a significant programming component. In our department, the data
structures course is arguably the most difficult programming course in the curricu-
lum.
Students should also work problems to develop their analytical abilities. I pro-
vide over 400 exercises and suggestions for programming projects. I urge readers
to take advantage of them.
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