Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Substitution
Processing...

Code Generator

Language

Generated Code

import re regex = re.compile(r"\$[^\$]*\$") test_str = ("$hello$\n\n" "$\n" "hello\n" "$\n\n" ".projection $I_{d,i} \\rightarrow M_{d,i} M_{d,0}$, where all the\n\n" "\\begin{itemize}\n" "\\item $M$ is atomic and finitely generated;\n" "\\item $M$ is cancellative;\n" "\\item $(M, \\le_L)$ and $(M, \\le_R)$ are lattices;\n" "\\item there exists an element $\\Delta \\in M$, called {\\it Garside element}, such that the set \n" "$L(\\Delta)= \\{ x \\in M; x\\le_L \\Delta\\}$ generates $M$ and is equal to $R(\\Delta)= \\{ x\\in M; \n" "x\\le_R \\Delta\\}$.\n" "\\end{itemize}\n\n" "Using the fact that is atomic and that $L(\\Delta)= \n" "\\{x \\in M; x \\le_L \\Delta\\} M \\pi_L(a) \\neq 1 a \\neq \n" "1 k \\partial_L^k(a)=1 k$ be the\n") subst = " " result = regex.sub(subst, test_str) if result: print(result)

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html