Shamil Salakhetdinov
shamil at users.mns.ru
Sun Sep 30 03:01:03 CDT 2007
<<<
However for more complicated
string operations like validating an email address, a regex would be very
suitable and doable in one line vs. many, many lines the other way.
>>>
Hi Mike,
That's clear, and the John's task is to get the speediest solution.
--
Shamil
-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Michael Bahr
Sent: Sunday, September 30, 2007 6:42 AM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Use Regex - Create Camel Case
Hi Shamil, yes regex's are slower in .Net due to I believe all the objects
overhead. For simple string operations regexes would probrably not be
effiecent BUT would be easier to write. However for more complicated
string operations like validating an email address, a regex would be very
suitable and doable in one line vs. many, many lines the other way.
Mike...
> Hi All,
>
> I wanted to note: I have seen somewhere an article about RegEx being
> considerably slower than a mere strings comparison etc. I cannot find this
> article now, can you?
>
> Here is a similar article on ColdFusion and Java (watch line wraps) -
>
>
http://www.bennadel.com/blog/410-Regular-Expression-Finds-vs-String-Finds.ht
> m
>
> The info above should be also true for C#/VB.NET (just remember there are
> no
> miracles in this world)...
>
> John, this could be critical information for you because of your computers
> processing zillion gigabytes of data - if that slowness of RegEx vs.
> string
> comparison operation proves to be true then mere chars/strings comparison
> and simple iteration over source string's char array could be the most
> effective solution, which will save you hours and hours of computing time:
>
> - define a 256 bytes long table (I guess you use extended ASCII (256 chars
> max) only John - right?) with to be stripped out chars marked by 1;
> - define upperCase flag;
> - allocate destination string, which is as long as the source one - use
> StringBuilder;
> - iterate source string and use current char's ASCII code as an index of a
> cell of array mentioned above:
> a) if the array's cell has value > 0 then the source char should be
> stripped out/skipped; set uppercase flag = true;
> b) if the array's cell has zero value and uppercase flag = true then
> uppercase current source char and copy it to the destination
> StringBuilder's; set uppercase flag = false;
> c) if the array's cell has zero value and uppercase flag = false then
> lower case current source char and copy it to the destination
> StringBuilder's string;
>
>
> Here is C# code:
>
>
> private static string[] delimiters = "
> |%|*|$|@|!|#|&|^|_|-|,|.|;|:|(|)".Split('|');
> private static byte[] sieve = new byte[255];
> private static bool initialized = false;
> static void JamOutBadChars()
> {
> if (!initialized)
> {
> sieve.Initialize();
> foreach (string delimiter in delimiters)
> {
> sieve[(int)delimiter.Substring(0, 1).ToCharArray()[0]] = 1;
> }
> initialized = true;
> }
> string[] test = {"John colby ",
> "%idiotic_Field*name&!@",
> " # hey#hey#Hey,hello_world$%#",
> "@#$this#is_a_test_of_the-emergency-broadcast-system "};
>
> foreach (string source in test)
> {
> StringBuilder result = new StringBuilder(source.Length);
> bool upperCase = true;
> foreach (char c in source.ToCharArray())
> {
> if (sieve[(int)c] > 0) upperCase = true;
> else if (upperCase)
> {
> result.Append(c.ToString().ToUpper());
> upperCase = false;
> }
> else result.Append(c.ToString().ToLower());
> }
> Console.WriteLine(source + " => {" + result + "}");
> }
> }
>
> --
> Shamil
>
>
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Michael Bahr
> Sent: Friday, September 28, 2007 10:25 PM
> To: Access Developers discussion and problem solving
> Subject: Re: [AccessD] Use Regex - Create Camel Case
>
> Hi John, here is one way to do it (although there are many ways to get the
> same end result). Mind you this is air code but hopefully should be
> enough to get you going. You will need to create the main loop within
> your code.
>
> Create a list of all delimiters that are used in your CSV files such as
> delimiters = '%|*|$|@|!|#|&|^|_|-|,|.|;|:| '
>
> then run through your CSV files line by line evaluating the line saving
> the line into an array
> thisarray = Split(line, delimiters)
>
> then run through the array performing a Ucase on the first letter of each
> word
> newline = ""
> For item=1 to ubound
> newline = newline & whatEverToCapFirstChar(item)
> Next item
>
> where ubound is the array size
>
>
> Now here are two scripts that do the same thing, one is Perl and the other
> is TCL. Both of these languages are open source and free and can be
> gotten at
> http://www.activestate.com/Products/languages.plex
>
> Perl:
>
> my $delimiters = '/:| |\%|\*|\$|\@|\!|\#|\&|^|_|-|,|\./';
> my @test = ("John colby",
> "%idiotic_Field*name",
> "hey#hey#Hey,hello_world",
> "this#is_a_test_of_the-emergency-broadcast-system");
>
> foreach my $item (@test) {
> my $temp = "";
> my @list = split ($delimiters, $item);
> foreach my $thing (@list) {
> $temp .= ucfirst($thing);
> }
> print "$temp\n";
>
> }
>
> Result
> d:\Perl>pascalcase.pl
> JohnColby
> IdioticFieldName
> HeyHeyHeyHelloWorld
> ThisIsATestOfTheEmergencyBroadcastSystem
>
> TCL:
>
> set delimiters {%|*|$|@|!|#|&|^|_|-|,|.|;|:|\ "}
> set test [list {John colby} {%idiotic_Field*name}
> {hey#hey#Hey,hello_world}
> {this#is_a_test_of_the-emergency-broadcast-system}]
>
>
> foreach item $test {
> set str ""
> set mylist [split $item, $delimiters]
> foreach thing $mylist {
> set s [string totitle $thing]
> set str "$str$s"
> }
> puts $str
>
> }
>
> Results
> D:\VisualTcl\Projects>tclsh pascalcase.tcl
> JohnColby
> IdioticFieldName
> HeyHeyHeyHelloWorld
> ThisIsATestOfTheEmergencyBroadcastSystem
>
>
> hth, Mike...
>
>
>> Folks,
>>
>> I am looking for a regex expression (preferably with explanation) for
>> taking
>> an expression and creating a camel case (or PascalCase) expression.
>>
>> I get CSV files with headers in them. All too often the eejits that
>> created
>> the databases they came from used embedded spaces or other special use
>> characters (!@#$%^&* etc) in their field names. I need to strip these
>> special characters out completely. I also need to upper case the valid
>> alpha character that follows any of these special characters.
>>
>> John colby becomes JohnColby
>> %idiotic_Field*name becomes IdioticFieldName
>>
>> Etc.
>>
>> It appears that Regex is the key (I am doing this in VB.Net) but until
>> today
>> I have never really tried to use RegEx and it ain't pretty!
>>
>> Any help in this would be much appreciated.
>>
>> John W. Colby
>> Colby Consulting
>> www.ColbyConsulting.com
>>
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>> http://databaseadvisors.com/mailman/listinfo/accessd
>> Website: http://www.databaseadvisors.com
>>
>
>
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