Solved

Ensuring an * only exists at beginning or end of string

Posted on 2009-05-08
6
211 Views
Last Modified: 2012-05-06
I need to verify that a string only contains * at the beginning r end of the string.

Conatining * in teh middle o fthe string is not ok.  
so *dsjdh   would be fine
*ddd* woudl be fine
whx* woudl be fine
but g*g would not be fine..

Anyone have anyidea how I can check this...


0
Comment
Question by:Prysson
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
6 Comments
 
LVL 1

Expert Comment

by:Acumentality
ID: 24337693

string s = "*aste*risk*";
bool inside = s.SubString(1, s.length-2).Contains("*");
//*asterisk is false, asterisk* is false, aste*risk is true, *aste*risk* is true

Open in new window

0
 
LVL 1

Accepted Solution

by:
Acumentality earned 500 total points
ID: 24337724
Sorry, some typos.
bool inside = s.Substring(1, s.Length-2).Contains("*");

Open in new window

0
 
LVL 16

Expert Comment

by:ToddBeaulieu
ID: 24337752
I'd probably just compare the results of a regular expression against the input string and if they match, it's good. The following example searches for an expression that allows 0 or more "*"'s the start of the string, 0 or more characters in the string, as long as they aren't "*"'s and then 0 or more "*"'s at the end.

This seems to work correctly, except as I typed this it was obvious the "or more" isn't what you want for the "*"s. There is an "exactly 1", but I assume you want to allow "zero" leading/trailing wildcards.

See the second block in the code snippet for a brute force approach.
using System.Text.RegularExpressions;
...
string pattern = @"^[\*]*[^\*]*[\*]*";
string search = @"*this is a * good example";
 
Regex regEx = new Regex(pattern);
Match match = regEx.Match(search);
 
if (match.Value == search)
    Console.WriteLine("Input string is good.");
else
    Console.WriteLine("Input string is bad.");
 
 
		string search = @"*this is* search string*";
		
		int i = search.IndexOf('*');
		int c = search.Length;
		bool failed = false;
		
		while(i < c && i != -1)
		{
			Console.WriteLine("Found a wildcard at position {0} in a string of {1} characters.", i, c);
			
			if (i != 0 && i != c-1)
			{
				failed = true;
				break;
			}
			
			i = search.IndexOf('*', i+1);
		}
 
		if (failed)
			Console.WriteLine("String is bad.");
		else
			Console.WriteLine("String is good.");

Open in new window

0
Creating Instructional Tutorials  

For Any Use & On Any Platform

Contextual Guidance at the moment of need helps your employees/users adopt software o& achieve even the most complex tasks instantly. Boost knowledge retention, software adoption & employee engagement with easy solution.

 
LVL 1

Expert Comment

by:Acumentality
ID: 24337905
For 0 or 1:
^[\*]?[^\*]*[\*]?

Open in new window

0
 
LVL 1

Expert Comment

by:Acumentality
ID: 24337916
Actually...
^[\*]?[^\*]*[\*]?$

Open in new window

0
 
LVL 16

Expert Comment

by:ToddBeaulieu
ID: 24337919
Acumentality: of course! :)
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article describes a simple method to resize a control at runtime.  It includes ready-to-use source code and a complete sample demonstration application.  We'll also talk about C# Extension Methods. Introduction In one of my applications…
Calculating holidays and working days is a function that is often needed yet it is not one found within the Framework. This article presents one approach to building a working-day calculator for use in .NET.
This video Micro Tutorial shows how to password-protect PDF files with free software. Many software products can do this, such as Adobe Acrobat (but not Adobe Reader), Nuance PaperPort, and Nuance Power PDF, but they are not free products. This vide…
In this video, viewers are given an introduction to using the Windows 10 Snipping Tool, how to quickly locate it when it's needed and also how make it always available with a single click of a mouse button, by pinning it to the Desktop Task Bar. Int…

691 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question