NS diagram is a description method used to replace the traditional flow chart. Based on the SP method, the NS diagram only contains the basic components of the following diagram, which respectively represent several standard control structures of the SP method.
Sequential type:
selection type:
WHILE repeat type and UNTIL repeat type
Multi-branch selection (case) type:
In the NS diagram, each "processing step" is represented by a box, and the so-called "processing step" can be a sentence or a sequence of sentences. If necessary, another box can be nested in the box. There is generally no limit to the depth of nesting. As long as the whole picture can fit on one page, it can only enter the box from the top and then go out from the bottom. There are no other entrances and exits, so the NS diagram restricts arbitrary control transfer and ensures a good structure of the program.
advantage:
- It forces the designer to think and describe his design plan according to the SP method, because it does not provide other description methods except for the symbols that indicate several standard structures, which effectively guarantees the quality of the design and thus also guarantees The quality of the program
- The NS image is intuitive and has good visibility. For example, the scope of the loop and the scope of the conditional statement are all clear at a glance, so it is easy to understand the design intent, which brings convenience to programming, review, selection of test cases, and maintenance.
- NS diagrams are simple, easy to learn and use, and can be used for software education and other aspects.
Disadvantages:
- Manual modification is more troublesome, which is the main reason why some people don't use it.
Recommended drawing tools:
1. Diagram Designer
download link Diagram Designer
2. Draw.io
download link Draw.io