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  • small world :)
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  • Hey Mary. Might be nice to add a credit to the original creator here. The name on the front of the slide seems to have been taken off. I have absolutely no issue with using stuff....happy to share...hence the stuff being on slideshare, but a credit back to the original would be appreciated.
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All meta languages

  1. 1. Symbol Meaning Predefined element Fixed element Path lines
  2. 2. ž Allowable Paths – follow the railroad from left to right and follow only one path
  3. 3. ž Eg, letter, sentence, program, variable name Variable
  4. 4. ž Reserved words,(Cannot use these words as variables (memory allocation) e.g., Dim, -+, 0, 1 Dim As
  5. 5. ž Eg, A Boolean Constant T F
  6. 6. ž Eg, A word Letter
  7. 7. ž Eg, a number that can be either positive or negative Digit _
  8. 8. Were created to make it easier to represent syntax
  9. 9. Symbol Meaning :: = Is defined as | Indicates choice between elements <> Non terminal symbol
  10. 10. BNF is a text based metalanguage that isread right to left. This way, syntax can berepresented by text, rather than diagrams
  11. 11. ž Invented to avoid the disadvantages of BNF.ž Easier to read, and less issues with things like repetition and optional elements
  12. 12. Symbol Meaning = Is defined as | Indicates choice between elements <> Non terminal symbol {} Encloses elements to be repeated [] Encloses optional elements
  13. 13. BNF EBNFž ::= ž =ž Boolean::=T|F ž Boolean=T|F
  14. 14. BNF EBNFž < > ž < >ž <Digit>::-0|1|2| ž <Digit>=0|1|2|ž <Letter>::-a|b|c ž <Letter>=a|b|c
  15. 15. BNF EBNFž Written as is ž Written as isž Dim ž Dimž If ž Ifž 0 ž 0ž 1 ž 1ž k ž k
  16. 16. BNF EBNFž Defined as | ž Defined as |ž Boolen::-T|F ž Boolen=T|F
  17. 17. BNF EBNFž  No Optional ž  [ ] Elements, so each option must be ž  Integer=[-] {<digit>} repeatedInteger::- - {<digit>} | {<digit>}
  18. 18. BNF EBNFž  No repetition ž  Indicated by { }ž  Repetition through ž  Word={Letter} recursion ž  Repeated zero or morež  Recursion is repetition times achieved through a ž  If it needs to be repeated process calling itself one or more times, it is written as ž  Word=Letter{Letter}
  19. 19. PublicDim Variable As Data Type Privat e
  20. 20. SingleShortBoolean Byte Char DateTimeDecimalDouble Int Long
  21. 21. Upper Case LowerCase UpperCas e Digit
  22. 22. 0987654321
  23. 23. ž Construct an EBNF diagram to describe a best practice, legal if statement.ž Should follow the following structure:ž If condition Then statements Else else statements

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