Functions/Get-LongestCommonSubstring.ps1
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function Get-LongestCommonSubstring { <# .SYNOPSIS Get the longest common substring of two strings. .DESCRIPTION Get the longest common substring of two strings. .EXAMPLE Get-LongestCommonSubstring 'Karolin' 'kathrin' -CaseSensitive .LINK https://fuzzystring.codeplex.com/ http://en.wikipedia.org/wiki/Longest_common_substring_problem https://communary.wordpress.com/ https://github.com/gravejester/Communary.PASM .NOTES Adapted to PowerShell from code by Kevin Jones (https://fuzzystring.codeplex.com/) Author: Øyvind Kallstad Date: 03.11.2014 Version: 1.0 #> [CmdletBinding()] param ( [Parameter(Position = 0)] [string] $String1, [Parameter(Position = 1)] [string] $String2, [Parameter()] [switch] $CaseSensitive ) if (-not($CaseSensitive)) { $String1 = $String1.ToLowerInvariant() $String2 = $String2.ToLowerInvariant() } $array = New-Object 'Object[,]' $String1.Length, $String2.Length $stringBuilder = New-Object System.Text.StringBuilder $maxLength = 0 $lastSubsBegin = 0 for ($i = 0; $i -lt $String1.Length; $i++) { for ($j = 0; $j -lt $String2.Length; $j++) { if ($String1[$i] -cne $String2[$j]) { $array[$i,$j] = 0 } else { if (($i -eq 0) -or ($j -eq 0)) { $array[$i,$j] = 1 } else { $array[$i,$j] = 1 + $array[($i - 1),($j - 1)] } if ($array[$i,$j] -gt $maxLength) { $maxLength = $array[$i,$j] $thisSubsBegin = $i - $array[$i,$j] + 1 if($lastSubsBegin -eq $thisSubsBegin) { [void]$stringBuilder.Append($String1[$i]) } else { $lastSubsBegin = $thisSubsBegin $stringBuilder.Length = 0 [void]$stringBuilder.Append($String1.Substring($lastSubsBegin, (($i + 1) - $lastSubsBegin))) } } } } } Write-Output $stringBuilder.ToString() } |