Complete if statement with strings and array of strings

Question

I have a page that has 3 variables. They look like this:

String[] Headers = new String[] { "Max Width", "Max Length", "Max Height" };
String currentHeader = (String)HttpContext.Current.Request.QueryString["ItemHas"] ?? "";
String checkString = (String)HttpContext.Current.Request.QueryString["ItemIn"] ?? "";

The checkString is a list of Headers delimited by a "|".

What is the easiest way to check if my currentHeader is in my Headers array and in my checkString String? I can do it but not in less than 20 lines of code. That seems like a less than optimal solution.

I would consider using a HashSet<string> for your Headers, that way you will have a much better lookup time. If you only have a couple headers, it might not be worth it though... — jjxtra
– jjxtra, Commented Apr 5, 2010 at 18:14

flq · Accepted Answer · 2010-04-05 17:21:49Z

5

checkString.Split('|').Contains(currentHeader) && Headers.Contains(currentHeader)

Using LINQ. Did I misunderstand something?

answered Apr 5, 2010 at 17:21

flq

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Peter · Accepted Answer · 2010-04-05 17:21:41Z

1

if (!string.IsNullOrEmpty(currentHeader) && Headers.Contains(currentHeader) && checkString.Split('|').Contains(currentHeader))

answered Apr 5, 2010 at 17:21

Peter

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Comments

JYelton · Accepted Answer · 2010-04-05 17:30:26Z

1

Write a quick utility method:

private bool IsInHeader(string[] _headers, string _findme)
{
    if (_headers == null || _findme == null) return false;
    foreach (string s in _headers)
    {
        if (_findme == s) return true;
    }
    return false;
}

edited Apr 5, 2010 at 17:30

answered Apr 5, 2010 at 17:21

JYelton

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2 Comments

n535 Over a year ago

And if _headers or _findme is null?

JYelton Over a year ago

Sorry I didn't see the line about the pipe-delimited string, but certainly you could modify the utility method to handle it. Also as Petoj suggested, the .Contains() method is concise.

Chris Van Opstal · Accepted Answer · 2010-04-05 18:05:42Z

1

Try this:

if (Headers.Contains(currentHeader) && checkString.Split('|').Contains(currentHeader)) {
    ....
}

And if you need it to be case-insensitive:

if (Headers.Contains(currentHeader, StringComparer.InvariantCultureIgnoreCase) 
    && checkString.Split('|').Contains(currentHeader, StringComparer.InvariantCultureIgnoreCase) {
    ....
}

edited Apr 5, 2010 at 18:05

answered Apr 5, 2010 at 17:22

Chris Van Opstal

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2 Comments

Jeffrey L Whitledge Over a year ago

+1 for culturally-sensative string comparisons! "Caf\u00E9" and "Cafe\u0301" look identical, they should compare as equal!

Jeffrey L Whitledge Over a year ago

But I just read the code, and you have a serious bug. If currentHeader contains a value that is a substring of one of the other delimited values in checkString, then your check will incorrectly return true. Don't make me take my vote away, please!

driis · Accepted Answer · 2010-04-05 17:22:20Z

0

Perhaps I am misunderstanding the question, but this should work:

var checks = checkString.Split('|');
if ( currentHeader.Contains(checkString) && Headers.Contains(checkString) )
{
   ....
}

answered Apr 5, 2010 at 17:22

driis

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