Page 201 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes Eventually, after coding the program, you must prepare to test it on the computer. This step
involves these phases:
(i) Desk-checking. This phase, similar to proofreading, is sometimes avoided by the
programmer who is looking for a shortcut and is eager to run the program on the computer
once it is written. However, with careful desk-checking you may discover several errors
and possibly save yourself time in the long run. In desk-checking you simply sit down and
mentally trace, or check, the logic of the program to attempt to ensure that it is error-free and
workable. Many organizations take this phase a step further with a walkthrough, a process
in which a group of programmers-your peers-review your program and offer suggestions
in a collegial way.
(ii) Translating. A translator is a program that (1) checks the syntax of your program to make
sure the programming language was used correctly, giving you all the syntax-error messages,
called diagnostics, and (2) then translates your program into a form the computer can
understand. A by-product of the process is that the translator tells you if you have improperly
used the programming language in some way. These types of mistakes are called syntax
errors. The translator produces descriptive error messages. For instance, if in FORTRAN
you mistakenly write N=2 *(I+J))-which has two closing parentheses instead of one-you
will get a message that says, “UNMATCHED PARENTHESES.” (Different translators may
provide different wording for error messages.) Programs are most commonly translated by
a compiler. A compiler translates your entire program at one time. The translation involves
your original program, called a source module, which is transformed by a compiler into an
object module. Prewritten programs from a system library may be added during the link/
load phase, which results in a load module. The load module can then be executed by the
computer.

(iii) Debugging. A term used extensively in programming, debugging means detecting, locating,
and correcting bugs (mistakes), usually by running the program. These bugs are logic errors,
such as telling a computer to repeat an operation but not telling it how to stop repeating.
In this phase you run the program using test data that you devise. You must plan the test
data carefully to make sure you test every part of the program.

9.3.1.5 Documenting the Program

Documenting is an ongoing, necessary process, although, as many programmers are, you may be
eager to pursue more exciting computer-centered activities. Documentation is a written detailed
description of the programming cycle and specific facts about the program. Typical program
documentation materials include the origin and nature of the problem, a brief narrative description
of the program, logic tools such as flowcharts and pseudocode, data-record descriptions, program
listings, and testing results. Comments in the program itself are also considered an essential part
of documentation. Many programmers document as they code. In a broader sense, program
documentation can be part of the documentation for an entire system.

The wise programmer continues to document the program throughout its design, development,
and testing. Documentation is needed to supplement human memory and to help organize
program planning. Also, documentation is critical to communicate with others who have an
interest in the program, especially other programmers who may be part of a programming team.
And, since turnover is high in the computer industry, written documentation is needed so that
those who come after you can make any necessary modifications in the program or track down
any errors that you missed.

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