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

Code Generator

Language

Generated Code

import re regex = re.compile(r"e.+[hktv]|oh?r.+m|p...?o|r.*ci|be?.i|^c?u|rad|sta|has|ct|fe", flags=re.MULTILINE) test_str = ("technetium\n" "promethium\n" "polonium\n" "astatine\n" "radon\n" "francium\n" "radium\n" "actinium\n" "thorium\n" "protactinium\n" "uranium\n" "neptunium\n" "plutonium\n" "americium\n" "curium\n" "berkelium\n" "californium\n" "einsteinium\n" "fermium\n" "mendelevium\n" "nobelium\n" "lawrencium\n" "rutherfordium\n" "dubnium\n" "seaborgium\n" "bohrium\n" "hassium\n" "meitnerium\n" "darmstadtium\n" "roentgenium\n" "copernicium\n" "ununtrium\n" "flerovium\n" "ununpentium\n" "livermorium\n" "ununseptium\n" "ununoctium\n\n" "hydrogen\n" "helium\n" "lithium\n" "beryllium\n" "boron\n" "carbon\n" "nitrogen\n" "oxygen\n" "fluorine\n" "neon\n" "sodium\n" "magnesium\n" "aluminium\n" "silicon\n" "phosphorus\n" "sulphur\n" "chlorine\n" "argon\n" "potassium\n" "calcium\n" "scandium\n" "titanium\n" "vanadium\n" "chromium\n" "manganese\n" "iron\n" "cobalt\n" "nickel\n" "copper\n" "zinc\n" "gallium\n" "germanium\n" "arsenic\n" "selenium\n" "bromine\n" "krypton\n" "rubidium\n" "strontium\n" "yttrium\n" "zirconium\n" "niobium\n" "molybdenum\n" "ruthenium\n" "rhodium\n" "palladium\n" "silver\n" "cadmium\n" "indium\n" "tin\n" "antimony\n" "tellurium\n" "iodine\n" "xenon\n" "caesium\n" "barium\n" "lanthanum\n" "cerium\n" "praseodymium\n" "neodymium\n" "samarium\n" "europium\n" "gadolinium\n" "terbium\n" "dysprosium\n" "holmium\n" "erbium\n" "thulium\n" "ytterbium\n" "lutetium\n" "hafnium\n" "tantalum\n" "tungsten\n" "rhenium\n" "osmium\n" "iridium\n" "platinum\n" "gold\n" "mercury\n" "thallium\n" "lead\n" "bismuth") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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