Programming process and flowchart


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Programming process and flowchart

  1. 1. Prepared by:Mr. Richard R. BasilioBSECE –T Dip IC
  2. 2.  The programmer’s job can be broken down into six programming steps: 1. Understand the problem 2. Plan the logic 3. Code the program 4. Translate the program into machine language 5. Test the program 6. Put the program into production
  3. 3.  Programmers must first understand what it is the user wants To understand the problem, you must analyze it Really understanding the problem may be one of the most difficult aspects of programming  The description of what the user needs may be vague  The user may not even really know what he or she wants  Users who think they know what they want frequently change their minds after seeing sample output
  4. 4.  Programmer plans the steps to the program, deciding what steps to include and how to order them Example  Planning tour  Planning party The two most common tools  flowcharts : pictorial representation  Pseudocode : English-like representation
  5. 5. start Flowcharts A pictorial representation of get the logical steps it takes to InputNumber solve a problem.  Uses Standardized Symbols calculatedAnswer = InputNumber * 2  Utilize Formula Notation  Typically Read from Top to print Bottom or from Left to Right on calculatedAnswer a Page stop
  6. 6.  Pseudocode An English-like representation of the logical steps it takes to solve a problem  pseudo – a prefix that means false  Short English-Like Statements  Not Standardized  Proper use of indentation Example start get InputNumber compute calculatedAnswer as InputNumber times 2 print calculatedAnswer stop
  7. 7.  Writing the program in one of more than 400 programming languages  Pascal, Assembly Language, C, C++, Java….. Concentrate on the syntax of the language  Exact instruction, symbol, …. ? Some very experienced programmers  successfully combining the logic planning and the actual instruction writing, or coding of the program, in one step  Writing a cinema scenario
  8. 8.  Objective  Each computer knows only one language, Machine Language.  High-level Languages must be translated into Machine Language Need to compiler or interpreter  Compiler catches every syntax error.  When writing a program, a programmer might need to recompile the code several times  An executable program is created only when the code is free of syntax errors
  9. 9.  Why does it need to be tested ?  Syntax Errors : by compile  Logical Errors : by test Test  Executing the program with some sample data  Seeing whether or not the results are logically correct.  being tested with many sets of data carefully Example Logically incorrect start get InputNumber compute calculatedAnswer as InputNumber times 20 print calculatedAnswer stop
  10. 10.  Once the program is tested adequately, it is ready for the organization to use. Putting the program into production might mean simply running the program once if it was written to satisfy a user’s request for a special list.
  11. 11.  By wikipedia definition: “A flowchart is a schematic representation of an algorithm or a stepwise process, showing the steps as boxes of various kinds, and their order by connecting these with arrows.” “Flowcharts are used in designing or documenting a process or program.”
  12. 12. Start/Stop Process Input/Output(Terminator) (Rectangle) (Parallelogram) Decision Connector Flowlines Predefined Process(Diamond) (Circle) (Arrows) (Rectangle)
  13. 13.  Input/Output Generalised Input/Output Block; reading data from an input medium or writing data to an output medium. This block Input/Output (Parallelogram) should be used in situation were data is being sent in and out of the processor via some sort of I/O peripheral.
  14. 14.  Process Any process step; an operation or group of operations that cause a change in value, form or Process location of the data. This (Rectangle) can consist of arithmetic or logical operators or even move commands.
  15. 15.  Flow line Sequence of operations and direction of data flow; arrowheads are required if linkage is not left-to-right Flowlines or top-to-bottom. (Arrows) Generally arrowheads are included to avoid confusion.
  16. 16.  Annotation Additional explanation or comments. This block is used for providing additional information to any other block in the flowchart.
  17. 17.  Decision Decision-making or switching type of operation, usually based on a comparison, that Decision determines which of a (Diamond) number of paths should be followed.
  18. 18.  Predefined Process One or more operation defined in more detail elsewhere, such as in a booklet or on a different flowchart, but not on Predefined Process (Rectangle) another part of the flowchart in which this symbol appears.
  19. 19.  Terminal Terminal point in a flowchart – stop, start or break in the line of flow. Start/Stop (Terminator)
  20. 20.  Connectors Entry to or exit from another part of the flowchart; if to or from step is on another page then the page reference should also be stated. Connector (Circle)
  21. 21.  Use a standardized flowcharting template, with clearly recognizable symbols. Follow ANSI recommendations for symbol use. Do not crowd or clutter the flowchart, ensure proper spacing between symbols. Number the pages of your flowchart sequentially. Specifically the title of program, the date and the author on each separate page.
  22. 22.  Chart the main line of data flow in the system or program first, then incorporate detail in later flowchart. Write within symbols avoid using too many words. If necessary use the annotation symbol. Choose wording to suit the anticipated readers of the flowchart.
  23. 23.  Be legible, neatness counts. If flowchart becomes complex use connector symbols to reduce the number of flow lines. Collect incoming and outgoing flow lines so that the number of lines entering or leaving a symbol are minimized.
  24. 24.  Use the flowchart as a guide when coding; change it when necessary to ensure the flowchart reflects the steps implemented in the code. Cross-reference portion of the flowchart to the source language code. Be consistent with the level of detail shown in the flowchart. Do not chart every detail, but do not leave out important details.
  25. 25.  Put yourself in the position of the reader; try to anticipate the reader’s problems in understanding the flowchart.
  26. 26.  Sequence If-then-else (Selection) While (Repetition)
  27. 27. entrance The SEQUENCE process is just a series of processes carried out one after the another. Most programs are represented at the highest level by the sequence , possible with a loop from exit end back to the beginning.
  28. 28.  The If-THEN-ELSE process entrance logically completes the binary decision block by providing two separate processes. One of the processes will be carried out in the each path from the binary decision. This is also called exit SELECTION.
  29. 29.  The WHILE process is allow entrance for the representation of a conditional loop structure within a program. The decision to execute the process is the loop is made prior to the execution of the process. exit This is also called REPETITION.