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
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

$re = '/\s+(-[0-9A-Za-z]+|--[A-Za-z0-9][\w-]+)/m'; $str = 'ignores position args ignores-this _and_this _2 but-not -a -xvzf -4 -6 -Targ ignores-echo ----------- ignores-mistaken --a did-you-mean -a --3-2-pulldown --3gpp-scan --64 --802_3-sap --802_3-type --90 --abi-call0 --action1 --action9 --appData --assume-utf16be --assume-utf16le --authValue --aws-sigv4 --background_compression --btf_encode --cipherText --Complain --contains_enumerator --data_replicas --disable-pcre2-8 --disable-pcre2grep-callout --disable-pcre2grep-callout-fork --disable-pcre2grep-jit --dns-ipv4-addr --dns-ipv6-addr --do-0x20-encode --do-x20-encode --dualprime-mpeg2 --eccpoint-L --enable-ebcdic-nl25 --enable-never-backslash-C --enable-pcre2-16 --enable-pcre2-32 --enable-pcre2grep-libbz2 --enable-pcre2grep-libz --enable-pcre2test-libedit --enable-pcre2test-libreadline --entityPath --expect100-timeout --exportedData --filter-A --filter-AAAA --filterwin2k --force-ipv4 --force-ipv6 --force-R5 --force-V4 --Foreground --fwdownload-mode3 --fwdownload-mode3-max --fwdownload-mode7 --gb18030 --GBR --hostpubmd5 --hostpubsha256 --http0 --http1 --http2 --http2-prior-knowledge --http3 --http3-only --ignoreDefinites --importData --Include --intra_dc_prec --ip6 --ip6-destination --ip6-destination-port --ip6-dport --ip6-dst --ip6-icmp-type --ip6-proto --ip6-protocol --ip6-source --ip6-source-port --ip6-sport --ip6-src --ip6-tclass --ipv4 --ipv6 --Iraw --Istdin --Istdout --jsonPolicy --keep-utf16 --keyPath --lang_exclude --Lc --Lee --linearize-pass1 --Lmac2 --Ln --logData --log-ip6 --Lx --mirror-above-4G --mirror-below-4G --netfilter6 --no-0x20-encode --no3d --no-altscan-mpeg2 --no-D --no-dhcpv4-interface --no-dummy-svcd-SOF --nr_methods --numBytes --Numeric --nvPath --oauth2-bearer --omit_journal_replay --output-Z1 --output-Z2 --p12-charset --pathList --pathOfKeyToDuplicate --pcrIndex --pcrList --pcrLog --pcrValue --plainText --policyPath --policyRef --post301 --post302 --post303 --prefer-ata12 --print0 --PROG-option --proxy1 --proxy-http2 --proxy-tls13-ciphers --proxy-tlsv1 --publicKey --publicKeyPath --qualifyingData --quiet-dhcp6 --quoteInfo --readimpliesX --reduction-2x2 --reduction-4x4 --replay_journal_only --searchPath --seek_bytes --set-recommended-min_free_kbytes --S-force --size_bytes --socks4 --socks4a --socks5 --socks5-basic --socks5-gssapi --socks5-gssapi-nec --socks5-gssapi-service --socks5-hostname --sslv2 --sslv3 --tls13-ciphers --tlsv1 --tpm2 --tpm2bPrivate --tpm2bPublic --type_trans --type_transition --UCS-2 --Version --warning-exit-0 --Wext --with-pcre2grep-bufsize --with-pcre2grep-max-bufsize --with-PROG --Wnp --Wp --x11 --x32 --x509certData'; preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0); // Print the entire match result var_dump($matches);

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 PHP, please visit: http://php.net/manual/en/ref.pcre.php