RegEx with multiple Var variable

Question

If you guys decide to put this code into your complier, you will notice that I get a Implicitly-typed local variables must be initlialized error on the var match. But i'm not too sure about how to go about doing this check (for text.count()) any other way. Sometimes my OCR will miss a letter or something and if it does, the number of characters will be less and that will make the match variable return a null...leaving me without a result.

Also, for bonus points, anyone that can help clean up my REGEX expression that'd be nice..i just started using it recently and i'm not tooo skilled in the semantics yet.

var match;
if (wordList[i].Text.Count() < 12)
{
    match = Regex.Match(wordList[i].Text, @"c[:;i]ty[!l1;:i/][5s][tuj!l/]z[i;:l]p[c1:;zs]", RegexOptions.IgnoreCase);
}
else
{
    match = Regex.Match(wordList[i].Text, @"c[:;i]ty[!l1;:i/][5s][tuj!l/][f!l1j;:i/]z[i;:l]p[c1:;zs]", RegexOptions.IgnoreCase);
}
if (match.Success)
{ ... }

Yuriy Faktorovich · Accepted Answer · 2013-07-24 17:02:20Z

3

You can't declare a var without initializing it. Use

Match match;

Or if you really must,

dynamic match;//I don't recommend this

Var is an implicitly typed variable, you must give it the value for it to infer the actual type. See here.

edited Jul 24, 2013 at 17:02

answered Jul 24, 2013 at 16:55

Yuriy Faktorovich

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4 Comments

MaylorTaylor Over a year ago

well I understand that. But doing var match = null; doesn't work. I know there has to be a way to do this.

Yuriy Faktorovich Over a year ago

@MaylorTaylor by doing var match = null you're still not telling the compiler what type match is.

NWard Over a year ago

You can't give a variable of type var a null type. Declare match as type Match. Edit: Yuriy beat me D:

David Sherret Over a year ago

@MaylorTaylor There is a way to do it and it's to tell the compiler what type match is by doing Match match; as this answer says.

zs2020 · Accepted Answer · 2013-07-24 17:08:02Z

0

Please checkout the doc.

Beginning in Visual C# 3.0, variables that are declared at method scope can have an implicit type var. An implicitly typed local variable is strongly typed just as if you had declared the type yourself, but the compiler determines the type.

When you declare a variable, you need to use explicitly typed way, or do

var match = new Match();

answered Jul 24, 2013 at 17:08

zs2020

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Comments

SLuck49 · Accepted Answer · 2013-07-24 17:08:58Z

0

You have to give the compiler something so it can infer what the type is. For example this will work:

var match = (Match)null;

Because the compiler knows var is supposed to be a Match.

Why you would want to do this over Match match; is beyond me, but it does work.

answered Jul 24, 2013 at 17:08

SLuck49

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Comments

Dr. Wily's Apprentice · Accepted Answer · 2013-07-24 17:21:49Z

Without looking at your regex patterns, I'll suggest that you could break your code down by separating the "pattern decision logic" from the rest of your code.

Below I've provided 2 separate examples for how to break this down. The first defines a DeterminePattern method that just returns which string to use as the regex pattern. The second defines a FindMatch method that returns the appropriate Match object.

Technically, either of these allows you to continue to use the var keyword, but in my mind that's not really that important...the benefit here, as I see it, is making the code simpler to read and understand. You can decide for yourself whether breaking the code down like this achieves that.

Example 1

private static string DeterminePattern(string input)
{
    if (input.Count() < 12)
    {
        return @"...";
    }

    return @"...";
}


var match = Regex.Match(wordList[i].Text, DeterminePattern(wordList[i].Text), RegexOptions.IgnoreCase);
if (match.Success)
{ ... }

Example 2

private static Match FindMatch(string input)
{
    if (input.Count() < 12)
    {
        return Regex.Match(input, @"...", RegexOptions.IgnoreCase);
    }

    return Regex.Match(input, @"...", RegexOptions.IgnoreCase);
}

var match = FindMatch(wordList[i].Text);
if (match.Success)
{ ... }

Nicholas Carey · Accepted Answer · 2013-07-24 17:55:56Z

Keep it DRY: Don't Repeat Yourself.

If you must use var (and even if you don't: what's the point of using var in this context especially?), this construct is better:

string text = wordList[i].Text ;
string pattern = text.Length < 12
               ? @"c[:;i]ty[!l1;:i/][5s][tuj!l/]z[i;:l]p[c1:;zs]"
               : @"c[:;i]ty[!l1;:i/][5s][tuj!l/][f!l1j;:i/]z[i;:l]p[c1:;zs]"
               ;
Match match = Regex.Match( text , pattern , RegexOptions.IgnoreCase ) ;

Or, better yet:

string text  = wordList[i].Text ;
Regex  rx    = text.Length < 12 ? Regex1 : Regex2 ;
Match  match = rx.Match( text , pattern , RegexOptions.IgnoreCase ) ;
.
.
.
private static readonly Regex1 = new Regex( @"c[:;i]ty[!l1;:i/][5s][tuj!l/]z[i;:l]p[c1:;zs]" , RegexOptions.IgnoreCase ) ;
private static readonly Regex2 = new Regex( @"c[:;i]ty[!l1;:i/][5s][tuj!l/][f!l1j;:i/]z[i;:l]p[c1:;zs]" , RegexOptions.IgnoreCase ) ;

And why on earth are you using Linq (Wordlist[i].Text.Count()) to get the length of a string? Strings already know length. There's no need to iterate over it to count characters: just ask the string how long it is by querying its Length property.

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