Case insensitive contains(string)

Question

Is there a way to make the following return true?

string title = "ASTRINGTOTEST";
title.Contains("string");

There doesn't seem to be an overload that allows me to set the case sensitivity..
Currently I UPPERCASE them both, but that's just silly.

UPDATE
The sillyness I refer to is the i18n issues that come with up- and down casing.

Answer 1

You could always just up or downcase the strings first.

string title = "string":
title.ToUpper().Contains("STRING")  // returns true

Oops, just saw that last bit. A case insensitive compare would *probably* do the same anyway, and if performance is not an issue, I don't see a problem with creating uppercase copies and comparing those. I could have sworn that I once saw a case-insensitive compare once...

Answer 2

You could use IndexOf() and pass StringComparison.OrdinalIgnoreCase

string title = "STRING";
bool contains = title.IndexOf("string", StringComparison.OrdinalIgnoreCase) >= 0;

Even better is defining a new extension method for string

public static bool Contains(this string source, string toCheck, StringComparison comp) {
  return source.IndexOf(toCheck, comp) >= 0;
}

string title = "STRING";
bool contains = title.Contains("string", StringComparison.OrdinalIgnoreCase);

Answer 3

If you want to call an extension method on strings you could do this...

public static class StringExtensions
{
    public static bool ContainsInsensitive(this string searchField, string searchTerm)
    {
        return searchField.ToLower().Contains(searchTerm.ToLower());
    }
}

Answer 4

You can use IndexOf() like this:

string title = "STRING";

if (title.IndexOf("string", 0, StringComparison.CurrentCultureIgnoreCase) != -1)
{
    // The string exists in the original
}

Since 0 (zero) can be an index, you check against -1.

Answer 5

Wish I could mark as duplicate: http://stackoverflow.com/questions/234591/upper-vs-lower-case

Shortcut to the accepted answer: http://msdn.microsoft.com/en-us/library/system.stringcomparer.aspx

Alternative solution (might work better in your case): http://stackoverflow.com/questions/234591/upper-vs-lower-case#234629

Answer 6

Try this method

     string query = string.Empty;
    query = searchString;
    string path = Server.MapPath("~/contacts.xml");
    XDocument xd = XDocument.Load(path);
    var results = (from items in xd.Elements("Company").Elements("Contact")
                   where items.Element("Name").Value.ToLowerInvariant().Contains(query.ToLowerInvariant())
                   select new
                   {
                       Id = items.Element("ID").Value,
                       Photo = (string)items.Element("photo").Value,
                       Name = (string)items.Element("Name").Value,
                       BloodGroup = (string)items.Element("Bg").Value,
                       Dob = (string)items.Element("dob").Value,
                       Anniversery = (string)items.Element("avd").Value,
                       Mobile = (string)items.Element("cnum").Value,
                       Designation = (string)items.Element("desig").Value,
                       Team = (string)items.Element("team").Value
                   });

Please vote up, if its your solution

Answer 7

Alternate solution using Regex:

bool contains = Regex.Match("StRiNG to search", "string", RegexOptions.IgnoreCase).Success;