Student version of EBNF BNF diagram presentation for BOS HSC Preliminary Software Design and Development

1. Meta Languages BNF/EBNF Kelly Bauer

2. 2 Basic Forms of metalanguage Railroad diagram (aka syntax structure diagrams) BNF/EBNF

3. Construct a railroad diagram of a legal if statement for Visual Basic HW

4. Railroad Diagrams

5. BNF/EBNF Were created to make it easier to represent syntax

6. Backus–Naur Form BNF is a text based metalanguage that is read right to left. This way, syntax can be represented by text, rather than diagrams

7. Extended Backus–Naur Form (EBNF) Invented to avoid the disadvantages of BNF. Easier to read, and less issues with things like repetition and optional elements

8. Is defined as BNF EBNF ::= Boolean::=T|F = Boolean=T|F

9. Non-terminal Elements BNF EBNF < > <Digit>::-0|1|2| <Letter>::-a|b|c < > <Digit>=0|1|2| <Letter>=a|b|c

10. Terminal Elements (eg, reserved words) BNF EBNF Written as is Dim If 0 1 k Written as is Dim If 0 1 k

11. Selection BNF EBNF Defined as | Boolen::-T|F Defined as | Boolen=T|F

12. Optional Elements BNF EBNF No Optional Elements, so each option must be repeated Integer::- - {<digit>} |{<digit>} [ ] Integer=[-] {<digit>}

13. Repetition BNF EBNF No repetition Repetition through recursion Recursion is repetition achieved through a process calling itself Text page 170 Indicated by { } Word={Letter} Repeated zero or more times If it needs to be repeated one or more times, it is written as Word=Letter{Letter}

14. an example

15. In EBNF Public Dim Variable As Data Type Private

16. Single Short Boolean Byte Char Date Time Decimal Double Int Long

17. Upper Case LowerCase UpperCase Digit

18. 0 9 8 7 6 5 4 3 2 1

19. In Visual Basic Construct an EBNF diagram to describe a best practice, legal if statement. Should follow the following structure: If condition Then statements Else elsestatements

20. Syllabus Sections?