BNF Study Notes

The Backus paradigm (Backus-naur Form) is a formal notation introduced by Backus and Naur to represent the syntax of a programming language. Specification

The characters in the quotation marks represent these themselves, and the quote represents the quotation marks
The character representing the syntax of the quotation.
<> the content in angle brackets indicates a required option
[] The contents of the square brackets indicate the optional
The contents of {} braces represent items that can be repeated 0 to countless times
| A vertical bar indicates either left or right selection
: = The meaning of the colon equals when defined as the advanced

BNF often uses recursive forms, such as:

<pp>:=<tt>|<tt><pp>

Represents an example of a PP consisting of one or more TT 201,700-degree star rematch 1001 for bomb number of BNF expression

<bomb number>: = <bomb term> | <bomb number> <bomb term>
<bomb term>: = <number> | ' (' <number> ') ' # ' (' <non-zero-digit> ') '
<number>: = <digit> | <digit> <number& gt;
<digit>: = ' 0 ' | ' 1 ' | ' 2 ' | ' 3 ' | ' 4 ' | ' 5 ' | ' 6 ' | ' 7 ' | ' 8 ' | ' 9 '
<non-zero-digit>: = ' 1 ' | ' 2 ' | ' 3 ' | ' 4 ' | ' 5 ' | ' 6 ' | ' 7 ' | ' 8 ' | ' 9 '

The

digit represents a single digit (0 to 9), and Non-zero-digit indicates that a non-0 digit (1 to 9)
number represents a value greater than or equal to one digit, and can have a leading 0
bomb term that represents a # or (number) # ( Non-zero-number)
Bomb number represents one or more bomb term 201,700-degree star rematch 1002 for the BNF representation of bomb expression

<bomb expression>: = <bomb term> | <bomb expression> <bomb term>
<bomb term>: = <bomb statement> | ' (' <bomb statement> ') ' # ' (' <number> ') '
<bomb statement>: = <bomb element> | <bomb St atement> <bomb element>
<bomb element>: = <digit> | '+' | '-' | ' * '
<normal expression>: = <norm term> | <normal expression> ' + ' <norm term> | <normal expr Ession> '-' <norm term>
<norm term>: = <number> | <norm term> ' * ' <number>
<n Umber>: = <digit> | <non-zero-digit> <number>
<digit>: = ' 0 ' | <non-zero-digit>
<non-zero-digit>: = ' 1 ' | ' 2 ' | ' 3 ' | ' 4 ' | ' 5 ' | ' 6 ' | ' 7 ' | ' 8 ' | ' 9 '

Non-zero-digit represents a non-0 number (1 to 9), digit represents a single digit (0 to 9)
Number means one digit and cannot have a leading 0 (can be 0)
Norm term indicates that one or more number is connected by *
Normal expression indicates that one or more norm term is connected by +,-

Bomb element represents a single number or an operator (+-*)
Bomb statement indicates that one or more bomb element is connected
Bomb term denotes a bomb statement or (Bomb statement) # (number)
Bomb expression denotes one or more bomb term connected sentiment

BNF is a very normative form, which can standardize language.