Nassi–Shneiderman diagram
diagram used to visualize the structure of a computer program
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 Stony Brook University. These diagrams are also called structograms, as they show a program's structures.
Overview
Following a top-down design, the problem at hand is reduced into smaller and smaller subproblems, until only simple statements and control flow constructs remain. Nassi–Shneiderman diagrams reflect this top-down decomposition in a straightforward way, using nested boxes to represent subproblems. Consistent with the philosophy of structured programming, Nassi–Shneiderman diagrams have no representation for a GOTO statement.
Nassi–Shneiderman diagrams are only rarely used for formal programming. Their abstraction level is close to structured program code and modifications require the whole diagram to be redrawn, but graphic editors removed that limitation. They clarify algorithms and high-level designs, which make them useful in teaching. They were included in Microsoft Visio and dozens of other software tools, such as the German EasyCODE.
In Germany, Nassi–Shneiderman diagrams were standardised in 1985 as DIN 66261.
“Nassi–Shneiderman diagram” enters the record as diagram used to visualize the structure of a computer program. Crown Archives preserves that source wording while asking what Nassi, Shneiderman and diagram can confirm, complicate or overturn.
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