2016.05.20-2016.05.26 Work hours and content this week

This week's study: This week to learn the NS diagram and pad map, the flow chart by a number of specific meaning of the graphics, process lines and brief textual description of the composition, it can clearly and clearly represent the process of the program. In the process of use, people find that the process line is not necessarily necessary, to this end, people have designed a new flowchart, it writes the entire program in a large block diagram, the large block diagram consists of a number of Small Basic block diagram, which is referred to as the diagram of N-S. The NS diagram is intuitive and has good visibility. For example, the scope of the loop, the scope of the condition statement is clear, so easy to understand the design intent, for programming, review, select test cases, maintenance has brought convenience; NS diagram is simple, easy to learn and use, can be used in software education and other aspects; a functional domain (that is, the scope of a particular control structure) is clearly defined And it can be intuitively seen from the N-S diagram, its control transfer can not be arbitrarily stipulated, must abide by the requirements of structured programming, it is easy to determine the scope of local data and global data, it is easy to express nested relationships, can also represent the hierarchy of the module. The PAD is an acronym for the Problem Analysis diagram (Problem analytical Diagram), a graphic presentation tool that has been presented by Ishina and others in Japan since 1974 to describe the detailed design of the software. Like the block diagram, the pad diagram can only describe several basic results that the structured program allows. Since the invention, has been promoted to a certain extent. It uses two-dimensional tree structure diagram to represent the control flow of the program, based on pad diagram, follow the mechanical tree Walk rules can easily write a program, it is easier to convert this diagram to program code.

The teacher gave us a problem, so that the following pseudo-program flowchart and the box diagram of the program START if p then while the Q do F end do ELSE block G N end Block end IF STOP. Here are my own drawings, and the teacher gave some different answers.

What to read this week:

Advantages of Pad Diagram 1. The program designed to use the pad symbol that represents the structural optimization control structure must be programmed program 2. The program structure described in the pad diagram is very clear. The leftmost vertical bar in the diagram is the main line of the program, the first layer of control structure. As the program level increases, the pad map gradually extends to the right, with each additional level, and the graph expands to the right by a vertical line. The total number of bars in a pad chart is the number of levels of the program; 3. Using pad diagram to show the program logic, easy to read, easy to understand, easy to remember. Pad diagram is a two-dimensional tree structure of the graph, the top left of the program at the end of the node start execution, top-down, from left to right in the order of execution; 4. It is easy to convert the pad diagram into a high-level program language source program, which can be automatically completed by software tools, eliminating manual coding and improving software reliability and software productivity. 5. Can be used to represent program logic, or to describe data structure 6. Pad Chart Symbols Support the use of top-down, stepwise refinement methods. At the beginning, the designer can define an abstract program, and use the "def" symbol to incrementally add detail as the design progresses until the detailed design is complete. The pad is a high-level programming language that provides a complete set of graphical symbols for each of the high-level programming languages used in Fortran,cobol and Pascal. Since each control statement has a graphical symbol corresponding to it, it is obvious that it is easier to convert the pad chart into a corresponding high-level language program. Pad is a kind of detailed design performance method with good visibility of program structure, unique structure, easy to compile, easy to check and easy to modify. With PAD can eliminate the software development process of the separation of design and production, but also to eliminate the production process of "human nature." Although it still needs to be programmed by people, once the development of the PAD programming automation system implementation, the computer can be automatically programmed from the pad, then the program logic is the software development process of artificial production of the final product. Obviously in the development time greatly saves, the development quality will be greatly improved. Cons: Not as easy to implement as flowcharts. The advantages of the NS diagram: First, it forces the designer to think about the SP method and describe his design, because in addition to representing the symbols of several standard structures, it no longer provides other means of description, which effectively guarantees the quality of the design, thus ensuring the quality of the program; second, the NS figure is intuitive, Has a good degree of visibility. For example, the scope of the loop, the scope of the condition statement is clear, so easy to understand the design intent, for programming, review, select test cases, maintenance has brought convenience; third, the NS diagram is simple, easy to learn and use, can be used in software education and other aspects. The disadvantage of the NS diagram: Manual modification is troublesome, which is the main reason some people do not use it.

2016.05.20-2016.05.26 Work hours and content this week