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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/
g

Test String

Code Generator

Language

Generated Code

$re = '/(in|out|ref) +w:(\d+) h:(\d+) fmt:(\w+) sar:(\d+)\/(\d+)(?: flags:0x[[:xdigit:]]+)?/'; $str = 'ffmpeg version N-86388-g3db98cad5c Copyright (c) 2000-2017 the FFmpeg developers built with Apple LLVM version 8.1.0 (clang-802.0.42) configuration: --enable-version3 --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 libavutil 55. 63.100 / 55. 63.100 libavcodec 57. 96.101 / 57. 96.101 libavformat 57. 72.101 / 57. 72.101 libavdevice 57. 7.100 / 57. 7.100 libavfilter 6. 91.100 / 6. 91.100 libswscale 4. 7.101 / 4. 7.101 libswresample 2. 8.100 / 2. 8.100 libpostproc 54. 6.100 / 54. 6.100 [Parsed_testsrc_0 @ 0x000000000000] size:320x240 rate:25/1 duration:-1.000000 sar:1/1 [Parsed_testsrc_1 @ 0x000000000000] size:640x360 rate:25/1 duration:-1.000000 sar:1/1 [Parsed_scale2ref_2 @ 0x000000000000] w:0 h:trunc((print(ow)*in_h+(in_w*7/2))/(in_h*7))*7 flags:\'bilinear\' interl:0 Stream mapping: scale2ref:default -> Stream #0:0 (rawvideo) Press [q] to stop, [?] for help [Parsed_testsrc_0 @ 0x000000000000] size:320x240 rate:25/1 duration:-1.000000 sar:1/1 [Parsed_testsrc_1 @ 0x000000000000] size:640x360 rate:25/1 duration:-1.000000 sar:1/1 [Parsed_scale2ref_2 @ 0x7fa20d40efa0] w:0 h:trunc((print(ow)*in_h+(in_w*7/2))/(in_h*7))*7 flags:\'bilinear\' interl:0 0.000000 [Parsed_scale2ref_2 @ 0x000000000000] The width was set to 0 which will use the width of the reference input (640) not the main input (320). [Parsed_scale2ref_2 @ 0x000000000000] Consider using: main_w [Parsed_scale2ref_2 @ 0x000000000000] The height was set to 0 which will use the height of the reference input (360) not the main input (240). [Parsed_scale2ref_2 @ 0x000000000000] Consider using: main_h [Parsed_scale2ref_2 @ 0x000000000000] in w:320 h:240 fmt:rgb24 sar:1/1 [Parsed_scale2ref_2 @ 0x000000000000] ref w:640 h:360 fmt:rgb24 sar:1/1 [Parsed_scale2ref_2 @ 0x000000000000] out w:640 h:360 fmt:rgb24 sar:3/4 flags:0x2 Output #0, md5, to \'pipe:\': Stream #0:0: Video: rawvideo, 1 reference frame (RGB[24] / 0x18424752), rgb24, 640x360 [SAR 3:4 DAR 4:3], q=2-31, 138240 kb/s, 25 fps, 25 tbn, 25 tbc (default) Metadata: encoder : Lavc rawvideo No more output streams to write to, finishing. MD5=cf8c2055d282268025d43c621e468a83 frame= 5 fps=0.0 q=-0.0 Lsize= 0kB time=00:00:00.20 bitrate= 1.5kbits/s speed=7.37x video:3375kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown Output file #0 (pipe:): Output stream #0:0 (video): 5 frames encoded; 5 packets muxed (3456000 bytes); Total: 5 packets (3456000 bytes) muxed '; 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