语言ns经典流程图_盒图、NS图（Nassi Shneiderman图）总结

A Nassi–Shneiderman diagram (NSD) in computer programming is a graphical design representation for structured programming. This type of diagram was developed in 1972 by Isaac Nassi and Ben Shneiderman who were both graduate students at SUNY-Stony Brook.

Nassi和Scheiderman提出了一种符合结构化程序设计原则的图形描述工具，叫作盒图，也叫做N-S图。任何一个N-S图，都是下面5种

NS图类似流程图，但所不同之处是NS图可以表示程序的结构。

依从上到下的设计，待处理的问题会分解成一些较小的副程序，最后只有简单的叙述及控制流程结构，NS图对应了上述的思维，利用嵌套的方块来表示副程序。NS图中没有对应Goto指令的表示，和结构化编程中不使用GOTO的理念一致。NS图的抽象层次接近结构化的代码，若程序重写，NS图就需重新绘制，不过NS图在简述程序及高级设计时相当方便。

NS图几乎是流程图的同构，任何的NS图都可以转换为流程图，而大部分的流程图也可以转换为NS图。其中只有像Goto指令或是C语言中针对循环的break及continue指令无法用NS图表示。

the fascinating history and evolution of structured flowcharts (usually called Nassi-Shneiderman Diagrams or structograms) goes back to 1972. As a graduate student, I got the idea while attending an ACM organized talk in New York by Michael Jackson on structured programming. If GOTOs were to be avoided, then shouldn't the lines in old flowcharts be avoided as well. Fifteen minutes of sketching led to the first ideas of sequence, conditionals and iteration.
Returning to Stony Brook, fellow graduate student Isaac Nassi shaped the ideas based on his more in-depth knowledge of structured programming principles. Together we wrote the original paper, which was quickly rejected for publication in the Communications of the ACM. So we sent it to the unrefereed ACM SIGPLAN (Special Interest Group on Programming Languages) Notices where it appeared in August 1973.
Nassi, I. and Shneiderman, B., Flowchart Techniques for Structured Programming, SIGPLAN Notices 8, 8 (August, 1973). (PDF file)
Since then it has been referenced thousands of times, spawned dozens of software implementations, been taught in dozens of textbooks, and is a required national standard in some countries. In Germany they are widely used and known as Struktogramme, standardized by DIN 66261 (November 1985), INFORMATION PROCESSING; NASSI-SHNEIDERMAN FLOWCHART SYMBOLS.
It's been exciting to see how this idea has spread, how others have extended it (sometimes abused it), and what influence it has had. I think its appeal has to do with its simplicity, originality, and ease of extending and embedding it. For visually oriented users, it provides a compact overview of a program that can show some relationships nicely. On the other hand, it may consume more paper than the code and be harder to scan for some details.
I believe it is helpful at early stages of program design for sketching the high-level modular design. For some people it is an aid in guiding thinking about nested conditional structures, in a more visual way than a decision table.

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