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"(?<comment>/\*.*?\*/|\-\-.*?$)", flags=re.MULTILINE | re.IGNORECASE | re.DOTALL) test_str = ("USE [master]\n" "GO\n\n" "IF OBJECT_ID('dbo.sp_foreach_db') IS NOT NULL\n" " DROP PROCEDURE [dbo].[sp_foreach_db] \n" "GO\n\n" "CREATE PROCEDURE [dbo].[sp_foreach_db] \n" "(\n" " @tsql NVARCHAR(MAX) = NULL\n" " ,@replacedatabasenamepattern NVARCHAR(20) = N'?'\n\n" " ,@break_on_error BIT = 1\n\n" " ,@db_name_like NVARCHAR(128) = NULL\n" " ,@db_name_in NVARCHAR(4000) = NULL\n" " ,@db_name_not_in NVARCHAR(4000) = NULL\n" " ,@db_use_system_db BIT = 0\n" " ,@db_use_temp_db BIT = 0\n\n" " ,@push_info_msg BIT = 1\n" ")\n" "WITH EXECUTE AS CALLER \n" "AS\n" "/*\n" "Version: 1.0.1.0\n" "Developer: Paw Jershauge\n" "Created: 18-03-2016 13:01:00\n" "*/\n" "BEGIN\n" " IF @tsql IS NULL\n" " RETURN 0;\n" " \n" " SET NOCOUNT ON;\n" " DECLARE @dbtsql NVARCHAR(MAX)\n" " ,@firecode NVARCHAR(MAX)\n" " ,@db_name NVARCHAR(128)\n" " ,@dbnames NVARCHAR(MAX) = N''\n" " ,@has_replacement BIT = 0\n" " ,@msg_str NVARCHAR(2044)\n\n" " SET @dbtsql = N'SELECT @dbnames += [name] + CHAR(10) FROM [master].[sys].[databases] WHERE [state] = 0'\n" " SET @dbtsql += IIF(ISNULL(@db_use_temp_db, 0) = 1, N'', N' AND [database_id] <> 2')\n" " SET @dbtsql += IIF(ISNULL(@db_use_system_db, 0) = 1, N'', N' AND [database_id] > 4')\n" " SET @dbtsql += IIF(NULLIF(@db_name_like, N'') IS NULL, N'', N' AND [name] LIKE ''' + @db_name_like + N'''')\n" " SET @dbtsql += IIF(NULLIF(@db_name_in, N'') IS NULL, N'', N' AND [name] IN (' + @db_name_in + N')')\n" " SET @dbtsql += IIF(NULLIF(@db_name_not_in, N'') IS NULL, N'', N' AND [name] NOT IN (' + @db_name_not_in + N')')\n" " \n" " EXEC sp_executesql @dbtsql, N'@dbnames NVARCHAR(MAX) OUTPUT', @dbnames = @dbnames OUTPUT;\n\n" " SELECT @has_replacement = CAST(CHARINDEX(ISNULL(@replacedatabasenamepattern, N'?'), @tsql) AS BIT)\n" " \n" " DECLARE cur_db CURSOR LOCAL FORWARD_ONLY FAST_FORWARD READ_ONLY FOR SELECT [value] FROM STRING_SPLIT(@dbnames, CHAR(10)) WHERE [value] <> N'' ORDER BY [value]\n" " OPEN cur_db\n" " FETCH NEXT FROM cur_db INTO @db_name\n" " WHILE @@FETCH_STATUS = 0 \n" " BEGIN \n" " BEGIN TRY\n" " SELECT @firecode = N'EXEC (N''' + IIF(@has_replacement = 0,N'Use [' + @db_name + N']; ', N'') + REPLACE(REPLACE(@tsql, ISNULL(@replacedatabasenamepattern, N'?'), @db_name), N'''', N'''''') + N''')'\n" " \n" " IF @push_info_msg = 1\n" " BEGIN\n" " SET @msg_str = CONVERT(NVARCHAR(40),GETDATE(), 121) + N':Executing on ' + @db_name\n" " RAISERROR (@msg_str, 0, 1) WITH NOWAIT\n" " END\n" " EXEC sp_executesql @firecode\n" " IF @push_info_msg = 1\n" " BEGIN\n" " SET @msg_str = CONVERT(NVARCHAR(40),GETDATE(), 121) + N':' + @db_name + N' Done!'\n" " RAISERROR (@msg_str, 0, 1) WITH NOWAIT\n" " END\n" " END TRY\n" " BEGIN CATCH\n" " SET @msg_str = 'Database ' + @db_name + ' failed with the following message:'\n" " RAISERROR (@msg_str, 0, 1) WITH NOWAIT\n" " SET @msg_str = ERROR_MESSAGE()\n" " RAISERROR (@msg_str, 0, 1) WITH NOWAIT --Workaround of the PRINT Command that is stacked and released in reverse order, on remote servers\n\n" " IF @break_on_error = 1\n" " THROW\n" " END CATCH\n\n" " FETCH NEXT FROM cur_db INTO @db_name\n" " END\n" " CLOSE cur_db\n" " DEALLOCATE cur_db\n\n" "END\n" "GO\n\n" "EXEC sys.sp_MS_marksystemobject sp_foreach_db\n" "GO") 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