Regular Expressions that I have been taught.
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Regular expression is a tool for matching patterns in text. With the help of regular expression you can find, match and replace text in strings.
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A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern.
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Module name re is imported to be used.
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\n
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Newline
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\s
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Space
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\t
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Tab
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\e
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Escape
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\r
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Return
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\d
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Any single character or number
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\D
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Anything but a number (non-digit character)
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\s
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Space
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\S
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Anything but a space
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\w
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Any character (A-Z, a-z, 0-9 and underscore)
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\W
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Anything but a character
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.
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Any single character except for a new line
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\b
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The white space around words
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\.
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A period
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match()
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Syntax - re.match(pattern, string, <flag=0>)
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search()
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For any pattern in the string - only the first match
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findall()
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Matches all occurrences
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split()
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Splits the string - forms an array
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replace()
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To replace one or more characters in a string
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{x,y}
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We expect x to y integers
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+
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Match one or more occurrences
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?
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Match 0 or 1 occurrence
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*
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Match 0 or more of the preceding expression (eg. x* will match occurrences of x)
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$
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Match the end of the string
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^
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Matching the beginning of a string
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Used as OR
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[]
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Displaying a range
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()
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To group the regular expressions
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