How can I make the line below case insensitive?
drUser["Enrolled"] =
(enrolledUsers.FindIndex(x => 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 => x.Username.Equals((string)drUser["Username"],
StringComparison.OrdinalIgnoreCase)));
Can anyone point out the problem?
The best way to do a case insensitive comparison in JavaScript is to use RegExp match() method with the i flag.
To perform a case-sensitive comparison of two char variables, simply use the Equals method, which, by default, performs a case-sensitive comparison. Performing a case-insensitive comparison requires that both characters be converted to their uppercase values (they could ...
Case-insensitive string comparison in C++ Here the logic is simple. We will convert the whole string into lowercase or uppercase strings, then compare them, and return the result. We have used the algorithm library to get the transform function to convert the string into lowercase string.
This is not the best practice in .NET framework (4 & +) 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.
You should use static String.Compare
function like following
x => String.Compare (x.Username, (string)drUser["Username"],
StringComparison.OrdinalIgnoreCase) == 0
Please use this for comparison:
string.Equals(a, b, StringComparison.CurrentCultureIgnoreCase);
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.
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;
/// <summary>
/// String helpers.
/// </summary>
public static class StringExtensions
{
/// <summary>
/// Compares two strings, set ignoreCase to true to ignore case comparison ('A' == 'a')
/// </summary>
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)
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);
}
}
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).
How about using StringComparison.CurrentCultureIgnoreCase
instead?
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