How to use string.contains() in a switch statement?

All replies

• 

  

  1

  Sign in to vote

  The simple answer is Yes, the switch won't work like that. Just use if() blocks.
  
  The more complex option if you're looking for specific keywords (i.e. like writing an SQL parser etc.) you can opt to use regular expressions to search for labelled matches then determine if any matches were found for each of your keywords. This will be less read-able but may likely net faster performance in cases where the search text and number of search conditions are larger.
  
  
  Start with if() blocks then if the performance is an issue read up on regular expressions. (regex)
  

  Tuesday, 19 February 2008 11:01 PM
• 

  

  1

  Sign in to vote

  I wish you had posted more code.

   

  Code Snippet

  public static void MethodA()

  {

  string text = "here is a string with some text";

  string[] testString = new string[] { "here", "is", "a", "text", "value" };

  foreach (string s in testString)

  {

  switch (text.Contains(s))

  {

  case true:

  MessageBox.Show(s + "was found");

  break;

  default:

  MessageBox.Show(s + "was not found");

  break;

  }

  }

  }

   

   

  Hope this helps.  I have a personal thing against using if.  I learned to program without them.  I've had to debug code that contained convoluted and nested statementes, which are hard to debug.   

   

  There's just too many variations on an if statement to make it easy to maintain.  Granted, in most cases switch or if will compile to nearly identical IL code.  But which is easier for a human being to read.  I challenge anyone to come up with a set of if statements that cannot be re-written using switch.  You cannot, because anything can be re-coded to use switch.

   

  Rudedog

  Wednesday, 20 February 2008 12:58 AM
• 

  

  0

  Sign in to vote

  What if I want to do this validation, but with different actions?
  
  
  

   string auxStr = subkey.ToLower();
                  switch (auxStr)
                  {
                      case "data source=":  
                                               system.engine = subkey.Substring(subkey.IndexOf("=") + 1); 
                                               break;
                      case "initial catalog=": 
                                               system.database = subkey.Substring(subkey.IndexOf("=") + 1); 
                                               break;
                      case "user id=":         
                                               system.user = subkey.Substring(subkey.IndexOf("=") + 1); 
                                               break;
                      case "password=":        
                                               system.pwd = subkey.Substring(subkey.IndexOf("=") + 1); 
                                               break;
                      default:                 
                                               break;
                  }

  Is that possible?
  
  Thanks in advance,
  
  Nuno

  ---

  Nuno Silva

  Saturday, 6 February 2010 10:15 PM
• 

  

  0

  Sign in to vote

  Yes that should work.
  
  -Romel Evans

  Sunday, 7 February 2010 5:50 PM
• 

  

  1

  Sign in to vote

  I think I should update this thread because it was one of my first results in google. It looks like this is possible as of C# 7.0.
  
  https://efficientuser.com/2017/03/15/c-7-pattern-matching-in-switch  

  • Proposed as answer by Pandiyan Murugan Wednesday, 9 January 2019 4:10 AM

  Tuesday, 8 January 2019 11:53 AM