a Library publication

Library Catalog No. DC1980
(reissued 20 August 2012)

Information packet on D-Charts, with articles from the late-1970s (Item 1 of 4)
by Kim Harris, et al.
e-Copyright © 2004–2016 < >
see also Part 1: Editor’s Introduction for Library Cat. No. DC1980


(Anonymous; 26 March 1980)

Using This Document

We are explaining D-Charts in four parts:

1. What is a D-Chart?

2. How to D-Chart

3. D-Chart Symbols and General Structures

4. Overall Example of a D-Chart

What is a D-Chart?

A D-Chart is a new and easier kind of flow chart. Basically, a D-Chart is a network of downward-flowing lines, with a few symbols, that graphically represents your program. We are grateful to Kim Harris for our knowledge of this superior method.

The D-Chart is a design tool, rather like a schematic. You work from your D-Chart; it is not a nasty bit of documentation to be provided after the program exists. Using a D-Chart makes coding easy; most of the work is already done. And, a D-Chart makes it possible for you to write structured definitions that will be “legal” in the language.

D-Charts are a better way of “flow charting” than the traditional ANSII Standard. They can be used effectively with either structured or non-structured programming. D-Charts are better because they are easier to write, and easier to read. As they are more compact, less space is used; this adds to their readability. None of the awkward boxes of ANSII flow charting is used.

How to D-Chart

There’s not much to it! The main line of the program flow is on the left (see Overall Example of a D-Chart). All constructs branch off to the right from it. Symbols for the beginning and ending of loops or constructs are numbered; this is especially helpful with nested constructs. Error symbols are also numbered; these numbers reference your error table.

These guidelines will help:

  • A D-Chart of the overall program is written as a design tool AS THE PROGRAM IS BEING THOUGHT OUT.
  • D-Charts of the specific program modules and submodules are written as these program portions are designed. New D-Charts are written as changes to existing code are designed.
  • D-Charts are written BEFORE CODING.

There are few rules in D-Charting, but they are important. Basically, they are:

  • One way in; one way out.
  • ALL structures must be closed. ONLY exception: a fatal program error that will stop the sequential program flow. (See “Error” symbol.)
  • In a conditional phase, the “true” portion of the phrase is on the right.
  • The “entry” (definition) name, at the top of the D-Chart, is underlined.

D-Chart Symbols

Arrows show the direction of program flow
“Switch” — beginning of a repetitive construct
Ending of repetitive construct; returns to switch
Branching structure (can be called a Test)
Multi-way decision
End of multi-way decision
(c)ondition to be tested
“Escape” — Construct terminator, unusual occurrences only.
Terminate construct; return to sequential program flow.
Error — For a fatal error that will terminate the sequential program flow. Circled # represents the error number.
General Structures
Linear — (Sequential Flow)

All words along the way will be executed.

Repetitive Statement:

Body of loop may or may not be executed.

Repetitive Statement:

Body of loop executes at least once.

Multi-Way Decision

Words along only one of the several paths will be executed; which path depends on the value of the top stack element. (This example shows four possible paths.)

below: Overall Example of a D-Chart
View an enlarged 1000 x 1271 pixel GIF image (52KB)
» next (Item 2 of 4)
» Item 2 of 4   (D-Charts, by Kim Harris, ca. 1978)
» Item 3 of 4   (D-Charts, by Kim Harris, September 1976)
» Item 4 of 4   (5 sample D-charts)

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