How can I do a case insensitive string comparison

Question

How can I make the line below case insensitive   drUser  Enrolled             enrolledUsers FindIndex x   gt  x Username     string drUser  Username       -1     I was given some advice earlier today that suggested I use    x Username Equals  string drUser  Username    StringComparison OrdinalIgnoreCase       the trouble is I can t get this to work  I ve tried the line below  this compiles but returns the wrong results  it returns enrolled users as unenrolled and unenrolled users as enrolled   drUser  Enrolled             enrolledUsers FindIndex x   gt  x Username Equals  string drUser  Username                                      StringComparison OrdinalIgnoreCase       Can anyone point out the problem

User · Answer

I think you will find more information in this link:

http://codeidol.com/community/dotnet/controlling-case-sensitivity-when-comparing-two-st/8873/

Use the Compare static method on the String class to compare the two strings. Whether the comparison is case-insensitive is determined by the third parameter of one of its overloads. For example:

string lowerCase = "abc";
string upperCase = "AbC";
int caseInsensitiveResult = string.Compare(lowerCase, upperCase,
  StringComparison.CurrentCultureIgnoreCase);
int caseSensitiveResult = string.Compare(lowerCase,
  StringComparison.CurrentCulture);

The caseSensitiveResult value is -1 (indicating that lowerCase is "less than" upperCase) and the caseInsensitiveResult is zero (indicating that lowerCase "equals" upperCase).

User · Answer

You should use static String Compare function like following  x   gt  String Compare  x Username   string drUser  Username                         StringComparison OrdinalIgnoreCase     0

User · Answer

I d like to write an extension method for EqualsIgnoreCase  public static class StringExtensions       public static bool  EqualsIgnoreCase this string strA  string strB                return strA  Equals strB  StringComparison CurrentCultureIgnoreCase

User · Answer

Please use this for comparison   string Equals a  b  StringComparison CurrentCultureIgnoreCase

User · Answer

Others answer are totally valid here  but somehow it takes some time to type StringComparison OrdinalIgnoreCase and also using String Compare   I ve coded simple String extension method  where you could specify if comparison is case sensitive or case senseless with boolean  attaching whole code snippet here   using System        lt summary gt      String helpers       lt  summary gt  public static class StringExtensions            lt summary gt          Compares two strings  set ignoreCase to true to ignore case comparison   A      a            lt  summary gt      public static bool CompareTo this string strA  string strB  bool ignoreCase                return String Compare strA  strB  ignoreCase     0            After that whole comparison shortens by 10 characters approximately - compare   Before using String extension   String Compare testFilename  testToStart true     0   After using String extension   testFilename CompareTo testToStart  true

User · Answer

This is not the best practice in  NET framework  4  amp     to check equality     String Compare x Username   string drUser  Username                       StringComparison OrdinalIgnoreCase     0   Use the following instead  String Equals x Username   string drUser  Username                        StringComparison OrdinalIgnoreCase     MSDN recommends         Use an overload of the String Equals method to test whether two    strings are equal    Use the String Compare and String CompareTo    methods to sort strings  not to check for equality

User · Answer

You can  although controverse  extend System String to provide a case insensitive comparison extension method   public static bool CIEquals this String a  String b        return a Equals b  StringComparison CurrentCultureIgnoreCase       and use as such   x Username CIEquals  string drUser  Username       C  allows you to create extension methods that can serve as syntax suggar in your project  quite useful I d say   It s not the answer and I know this question is old and solved  I just wanted to add these bits

User · Answer

you can always use functions   ToLower     ToUpper     convert your strings and then compare them     Good Luck

User · Answer

How about using StringComparison CurrentCultureIgnoreCase instead

[c#] How can I do a case insensitive string comparison?

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