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

r"
"
g

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "((?:if|for|while)\\s+?[^:]*?:\\n)|(else\\s*?:\\n)|(else\\s+?if[^:]*?:\\n)"; final String string = "import datetime\n" + "import difflib\n" + "import hashlib\n" + "import random\n" + "import re\n\n" + "from annoying.functions import get_object_or_None\n" + "from django.conf import settings\n" + "from django.contrib.auth.models import User\n" + "from django.db import models\n" + "from markdown_deux import markdown\n" + "from pygments import highlight\n" + "from pygments.formatters import HtmlFormatter\n" + "from pygments.lexers import get_lexer_by_name\n" + "from pygments.util import ClassNotFound\n" + "from snipts.utils import slugify_uniquely\n" + "from taggit.managers import TaggableManager\n" + "from taggit.utils import edit_string_for_tags\n" + "from teams.models import Team\n\n\n" + "class Snipt(models.Model):\n" + " \"\"\"An individual Snipt.\"\"\"\n\n" + " user = models.ForeignKey(User, blank=True, null=True, on_delete=models.CASCADE)\n" + " last_user_saved = models.ForeignKey(\n" + " User,\n" + " blank=True,\n" + " null=True,\n" + " related_name=\"last_user_saved\",\n" + " on_delete=models.CASCADE,\n" + " )\n\n" + " title = models.CharField(max_length=255, blank=True, null=True, default=\"Untitled\")\n" + " slug = models.SlugField(max_length=255, blank=True)\n" + " custom_slug = models.SlugField(max_length=255, blank=True)\n" + " tags = TaggableManager()\n\n" + " lexer = models.CharField(max_length=50)\n" + " code = models.TextField()\n" + " meta = models.TextField(blank=True, null=True)\n" + " description = models.TextField(blank=True, null=True)\n" + " stylized = models.TextField(blank=True, null=True)\n" + " stylized_min = models.TextField(blank=True, null=True)\n" + " embedded = models.TextField(blank=True, null=True)\n" + " line_count = models.IntegerField(blank=True, null=True, default=None)\n\n" + " key = models.CharField(max_length=100, blank=True, null=True)\n" + " public = models.BooleanField(default=False)\n" + " secure = models.BooleanField(default=False)\n" + " blog_post = models.BooleanField(default=False)\n\n" + " views = models.IntegerField(default=0)\n\n" + " created = models.DateTimeField(auto_now_add=True, editable=False)\n" + " modified = models.DateTimeField(auto_now=True, editable=False)\n" + " publish_date = models.DateTimeField(blank=True, null=True)\n\n" + " def _unidiff_output(self, expected, actual):\n" + " expected = expected.splitlines(1)\n" + " actual = actual.splitlines(1)\n\n" + " diff = difflib.unified_diff(expected, actual)\n\n" + " return \"\".join(diff)\n\n" + " def __init__(self, *args, **kwargs):\n" + " super(Snipt, self).__init__(*args, **kwargs)\n" + " self.original_code = self.code\n\n" + " def save(self, *args, **kwargs):\n\n" + " if not self.slug:\n" + " self.slug = slugify_uniquely(self.title, Snipt)\n\n" + " if not self.key:\n" + " self.key = hashlib.md5(\n" + " (\n" + " self.slug + str(datetime.datetime.now()) + str(random.random())\n" + " ).encode(\"utf-8\")\n" + " ).hexdigest()\n\n" + " if self.lexer == \"markdown\":\n" + " self.stylized = markdown(self.code, \"default\")\n\n" + " # Snipt embeds\n" + " for match in re.findall('\\[\\[(\\w{32})\\]\\]', self.stylized):\n" + " self.stylized = self.stylized.replace('[[' + str(match) + ']]',\n" + " \"\"\"\n" + " <script type=\"text/javascript\"\n" + " src=\"https://snipt.net/embed/{}/?snipt\">\n" + " </script>\n" + " <div id=\"snipt-embed-{}\"></div>\"\"\".format(\n" + " match, match\n" + " ),\n" + " )\n\n" + " # YouTube embeds\n" + " for match in re.findall(\n" + " \"\\[\\[youtube-(\\w{11})\\-(\\d+)x(\\d+)\\]\\]\", self.stylized\n" + " ):\n" + " self.stylized = self.stylized.replace(\n" + " \"[[youtube-{}-{}x{}]]\".format(\n" + " str(match[0]), str(match[1]), str(match[2])\n" + " ),\n" + " \"\"\"<iframe width=\"{}\" height=\"{}\"\n" + " src=\"https://www.youtube.com/embed/{}\"\n" + " frameborder=\"0\" allowfullscreen></iframe>\"\"\".format(\n" + " match[1], match[2], match[0]\n" + " ),\n" + " )\n\n" + " # Vimeo embeds\n" + " for match in re.findall(\"\\[\\[vimeo-(\\d+)\\-(\\d+)x(\\d+)\\]\\]\", self.stylized):\n" + " self.stylized = self.stylized.replace(\n" + " \"[[vimeo-{}-{}x{}]]\".format(\n" + " str(match[0]), str(match[1]), str(match[2])\n" + " ),\n" + " \"\"\"<iframe src=\"https://player.vimeo.com/video/{}\"\n" + " width=\"{}\" height=\"{}\" frameborder=\"0\"\n" + " webkitAllowFullScreen mozallowfullscreen\n" + " allowFullScreen></iframe>\"\"\".format(\n" + " match[0], match[1], match[2]\n" + " ),\n" + " )\n\n" + " # Tweet embeds\n" + " for match in re.findall(\"\\[\\[tweet-(\\d+)\\]\\]\", self.stylized):\n" + " self.stylized = self.stylized.replace(\n" + " \"[[tweet-{}]]\".format(str(match)),\n" + " '<div class=\"embedded-tweet\" data-tweet-id=\"{}\"></div>'.format(\n" + " str(match)\n" + " ),\n" + " )\n\n" + " # Parse Snipt usernames\n" + " for match in re.findall('@(\\w+) ', self.stylized):\n\n" + " # Try and get the Snipt user by username.\n" + " user = get_object_or_None(User, username=match)\n\n" + " if user:\n" + " url = user.profile.get_user_profile_url()\n" + " self.stylized = self.stylized.replace(\n" + " \"@{} \".format(str(match)),\n" + " '<a href=\"{}\">@{}</a> '.format(url, match),\n" + " )\n\n" + " else:\n" + " self.stylized = highlight(\n" + " self.code,\n" + " get_lexer_by_name(self.lexer, encoding=\"UTF-8\"),\n" + " HtmlFormatter(\n" + " linenos=\"table\", anchorlinenos=True, lineanchors=\"L\", linespans=\"L\"\n" + " ),\n" + " )\n" + " self.line_count = len(self.code.split(\"\\n\"))\n\n" + " if self.lexer == \"markdown\":\n" + " lexer_for_embedded = \"text\"\n" + " else if asdgh:\n" + " asd\n" + " else:\n" + " lexer_for_embedded = self.lexer\n\n" + " embedded = highlight(\n" + " self.code,\n" + " get_lexer_by_name(lexer_for_embedded, encoding=\"UTF-8\"),\n" + " HtmlFormatter(\n" + " style=\"native\",\n" + " noclasses=True,\n" + " prestyles=\"\"\"\n" + " background-color: #1C1C1C;\n" + " border-radius: 5px;\n" + " color: #D0D0D0;\n" + " display: block;\n" + " font: 11px Monaco, monospace;\n" + " margin: 0;\n" + " overflow: auto;\n" + " padding: 15px;\n" + " -webkit-border-radius: 5px;\n" + " -moz-border-radius: 5px;\n" + " \"\"\",\n" + " ),\n" + " )\n" + " embedded = (\n" + " embedded.replace('\\\\\"', '\\\\\\\\\"')\n" + " .replace(\"'\", \"\\\\'\")\n" + " .replace(\"\\\\\", \"\\\\\\\\\")\n" + " .replace(\"background: #202020\", \"\")\n" + " )\n" + " self.embedded = embedded\n\n" + " snipt = super(Snipt, self).save(*args, **kwargs)\n\n" + " diff = self._unidiff_output(self.original_code or \"\", self.code)\n\n" + " if diff != \"\":\n" + " log_entry = SniptLogEntry(\n" + " user=self.last_user_saved, snipt=self, code=self.code, diff=diff\n" + " )\n" + " log_entry.save()\n\n" + " return snipt\n\n" + " def __unicode__(self):\n" + " return self.title\n\n" + " def favs(self):\n" + " return Favorite.objects.filter(snipt=self).count()\n\n" + " def get_stylized_min(self):\n" + " if self.stylized_min is None:\n" + " if self.lexer == \"markdown\":\n" + " self.stylized_min = markdown(self.code[:1000], \"default\")\n" + " else:\n" + " self.stylized_min = highlight(\n" + " self.code[:1000],\n" + " get_lexer_by_name(self.lexer, encoding=\"UTF-8\"),\n" + " HtmlFormatter(linenos=\"table\", linenospecial=1, lineanchors=\"line\"),\n" + " )\n" + " return self.stylized_min\n\n" + " def get_absolute_url(self):\n\n" + " if self.blog_post:\n" + " if self.user.profile.blog_domain:\n" + " return u\"http://{}/{}/\".format(\n" + " self.user.profile.blog_domain.split(\" \")[0], self.slug\n" + " )\n" + " else:\n" + " return u'https://{}.snipt.net/{}/'.format(\n" + " self.user.username.replace('_', '-'), self.slug)\n\n" + " if self.custom_slug:\n" + " return u\"/{}/\".format(self.custom_slug)\n\n" + " if self.public:\n" + " return u\"/{}/{}/\".format(self.user.username, self.slug)\n" + " else:\n" + " return u\"/{}/{}/?key={}\".format(self.user.username, self.slug, self.key)\n\n" + " def get_full_absolute_url(self):\n\n" + " if self.blog_post:\n" + " if self.user.profile.blog_domain:\n" + " return u\"http://{}/{}/\".format(\n" + " self.user.profile.blog_domain.split(\" \")[0], self.slug\n" + " )\n" + " else:\n" + " return u'https://{}.snipt.net/{}/'.format(\n" + " self.user.username, self.slug)\n\n" + " if self.public:\n" + " return u\"/{}/{}/\".format(self.user.username, self.slug)\n" + " else:\n" + " return u\"/{}/{}/?key={}\".format(self.user.username, self.slug, self.key)\n\n" + " def get_download_url(self):\n\n" + " try:\n" + " lexer_obj = get_lexer_by_name(self.lexer)\n" + " except ClassNotFound:\n" + " lexer_obj = None\n\n" + " if lexer_obj and lexer_obj.filenames:\n" + " filename = lexer_obj.filenames[0].replace(\"*\", self.slug)\n" + " else:\n" + " if self.lexer == \"markdown\":\n" + " filename = u\"{}.md\".format(self.slug)\n" + " else:\n" + " filename = u\"{}.txt\".format(self.slug)\n\n" + " return u\"/download/{}/{}\".format(self.key, filename)\n\n" + " def get_embed_url(self):\n\n" + " if settings.DEBUG:\n" + " root = 'http://local.snipt.net'\n" + " else:\n" + " root = 'https://snipt.net'\n\n" + " return \"{}/embed/{}/\".format(root, self.key)\n\n" + " def get_raw_url(self):\n" + " return \"/raw/{}/\".format(self.key)\n\n" + " @property\n" + " def sorted_tags(self):\n" + " return self.tags.all().order_by(\"name\")\n\n" + " @property\n" + " def tags_list(self):\n" + " return edit_string_for_tags(self.tags.all())\n\n" + " @property\n" + " def lexer_name(self):\n" + " if self.lexer == \"markdown\":\n" + " return \"Markdown\"\n" + " else:\n" + " return get_lexer_by_name(self.lexer).name\n\n" + " def is_authorized_user(self, user):\n" + " if self.user == user:\n" + " return True\n" + " if self.user.profile.is_a_team:\n" + " team = Team.objects.get(user=self.user, disabled=False)\n" + " return team.user_is_member(user)\n" + " return False\n\n\n" + "class SniptLogEntry(models.Model):\n" + " \"\"\"An individual log entry for a Snipt changeset.\"\"\"\n\n" + " user = models.ForeignKey(User, on_delete=models.CASCADE)\n" + " snipt = models.ForeignKey(Snipt, on_delete=models.CASCADE)\n\n" + " code = models.TextField()\n" + " diff = models.TextField()\n\n" + " created = models.DateTimeField(auto_now_add=True, editable=False)\n" + " modified = models.DateTimeField(auto_now=True, editable=False)\n\n" + " @property\n" + " def snipt_name(self):\n" + " return self.snipt.title or \"Untitled\"\n\n\n" + "class SniptSecureView(models.Model):\n" + " \"\"\"A single view to a secure snipt.\"\"\"\n\n" + " user = models.ForeignKey(User, on_delete=models.CASCADE)\n" + " snipt = models.ForeignKey(Snipt, on_delete=models.CASCADE)\n\n" + " created = models.DateTimeField(auto_now_add=True, editable=False)\n" + " modified = models.DateTimeField(auto_now=True, editable=False)\n\n" + " @property\n" + " def snipt_name(self):\n" + " return self.snipt.title or \"Untitled\"\n\n\n" + "class Favorite(models.Model):\n" + " snipt = models.ForeignKey(Snipt, on_delete=models.CASCADE)\n" + " user = models.ForeignKey(User, on_delete=models.CASCADE)\n\n" + " created = models.DateTimeField(auto_now_add=True, editable=False)\n" + " modified = models.DateTimeField(auto_now=True, editable=False)\n\n" + " def __unicode__(self):\n" + " return u\"{} favorited by {}\".format(self.snipt.title, self.user.username)\n\n"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html