C# Comparing strings with different case

Question

I'm reading a username and then checking to see if exists in another database table, the problem is whilst the username is the same the case maybe different and is preventing it from finding a match example jsmith and JSmith or JSMITH.

How can I fix this? Should I lower the case when writing to the first database or can I alter my code below when I'm comparing the two?

drUser["Enrolled"] = 
    (enrolledUsers.FindIndex(x => x.Username == (string)drUser["Username"]) != -1);

UPDATE:

Still struggling with this, the code below compiles but doesn't give the correct result, when viewing enrolled users I see those that aren't enrolled, when viewing those that are not enrolled I see 1 that is enrolled but their username case is the same in each datababse. Have I formatted the code below correctly?

drUser["Enrolled"] = (enrolledUsers.FindIndex(x => x.Username.Equals((string)drUser["Username"], StringComparison.OrdinalIgnoreCase)));

Thanks Jamie

Answer 1

You need to cal the Equals method, which takes a StringComparison parameter.

For example:

x.Username.Equals((string)drUser["Username"], StringComparison.OrdinalIgnoreCase)

If x.Username can be null, you should call the static Equals method:

String.Equals(x.Username, (string)drUser["Username"], StringComparison.OrdinalIgnoreCase)

Otherwise, x.Username.Equals can throw a NullReferenceException.

Answer 2

The preferred way to do this, is to specify the string comparison by using something like

string.Equals(x.Username, (string)drUser["Username"], StringComparison.OrdinalIgnoreCase

to do the equality check, instead of "=="

Answer 3

You should use the String.Compare method

drUser["Enrolled"] = (enrolledUsers.FindIndex(x => 
                        string.Compare(x.Username,(string)drUser["Username"], false) == 0) != -1);

Answer 4

How about using ToUpper().

 if(!(dr["Enrolled"] == null || dr["Username"] == null))
 {
    if(dr["Enrolled"].ToString().ToUpperInvariant()== dr["Username"].ToString().ToUpperInvariant())
    {
        //Do Something
    }
}

Answer 5

Have you tried this?

string userName = (string)drUser["Username"];
bool enrolled = enrolledUsers.Exists(x =>
  string.Equals(x.Name, userName, StringComparison.CurrentCultureIgnoreCase));

Is there a reason you are using FindIndex instead?

Answer 6

try the string.compare method. all overloads

Or a more specific one

If nothing else, I hope it educates.