5.4 Structured Program Design and Software Engineering

5.4.1 Program Design and Software Engineering

• Specifications
• Design
  • Software Engineering
  • Optimization
  • Viability, low level issues.
  • Economic issues. See and READ the book The Mythical Man-month by Frederick P. (Phillips) Brooks.
• Coding
• Documentation

  Self documenting code is an "ideal". It involves many different features. A short list that you might consider follows:

  • Good us of white space.
  • Description of overall function at the beginning of the program.
  • Use of good variable names.
  • Define variables in Alphabetic order. Give the units that the variavle is in in the comments.
  • Keep code modules under 10 pages of code.
  • If the code changes, make sure that the comments reflect the change.
• Testing

  How do you test ALL of the code?

• Maintenance
• The "Year 2000 Problem"

5.4.2 Procedural Programming Languages

• COBOL
  A busines and accounting oriented language. Good for writing with money, inventory, and data base applications. Very large base of installed programs. Expect a major demand for programmers to fix the "Year 2000" problem. See: Nance & Naps pages 12 & 871.
• C See Kernighan and Richie's. This is a "systems" programming language. It runs on "all" platforms. Many cross platform compilers also exist. It is used for most all systems level programming. The language has most of the features of the DECPDP-11 assembly language.
• C++ Object Oriented version of "C". Better code re-usability and programmed productivity than "C". See: Nance & Naps Chapter 17 page 825.
• FORTRAN The first "high" level language. Still used for scientific programming. A lot of legacy code. Much of the "super-computer" programming is done in a vector version of FORTRAN.
• LISP A language commonly used in AI. The FSF emacs text editor includes an emacs interpreter.
• Forth An interpreted stack language developed at the UofA on a PDP-11/60 that was then transfered to PCC electronics technology department.
• Prolog A fourth generation language.
• Java A write once run anywhere language. Object oriented (See: Nance & Naps Chapter 17 page 825). Misses some of the major drawbacks of "C" and "C++". No address pointers. Better string handling.
• BASIC A "simple" programming language that use to come with MS-DOS. Originally designed for teaching programming. Has evolved from an unstructured interpreted language to a structured compile-and-run language.
• Visual BASIC
• Modula 2 An AI language.
• APL An interpreted scientific programming language.
• PL/1 IBM's merger of FORTRAN, ALGOL, and COBOL.
• SQL A database access language.

Some languages are interpreted. Other languages are compiled. Compiled languages "normally" execute faster than interpreted languages.

Structured and unstructured languages.

The GOTO statement has, at times, been poorly used. It can lead to code that is hard to understand and harder to mantain. There are some very good places to use it. For example, breaking out of a nested loop structure to a specific point in the nesting. The "perl" programming language has an interesting solution to this problem. When you use a break or continue statement it specifies which loop you are breaking or continuing. See: Nance & Naps Appendix 7 page A34.