Ignore case and compare in C#

Question

How to convert the string to uppercase before performing a compare, or is it possible to compare the string by ignoring the case

 if (Convert.ToString(txt_SecAns.Text.Trim()).ToUpper() == 
     Convert.ToString(hidden_secans.Value).ToUpper())

Solution 1

use this:

var result = String.Compare("AA", "aa", StringComparison.OrdinalIgnoreCase);

String.Compare Method (String, String, Boolean)

Solution 2

Case-insensitive string comparison is done like this in C#:

string.Equals("stringa", "stringb", StringComparison.CurrentCultureIgnoreCase)

Watch out! this code is culture dependant; there are several other options available, see http://msdn.microsoft.com/en-us/library/system.stringcomparison.aspx.

Solution 3

Well, you can use String.Equals(String,StringComparison) method. Just pass it StringComparison.InvariantCultureIgnoreCase or StringComparison.CurrentCultureIgnoreCase depending on your objectives...

Solution 4

From MSDN:

String.Compare Method (String, String, Boolean):

public static int Compare(
    string strA,
    string strB,
    bool ignoreCase
)

so in your case:

if( String.Compare(txt_SecAns.Text.Trim(), hidden_secans.Value, true) == 0) 

Solution 5

Use StringComparison.CurrentCultureIgnoreCase:

if (txt_SecAns.Text.Trim().Equals(hidden_secans.Value.ToString(), StringComparison.CurrentCultureIgnoreCase))

View more solutions

Comments

[CodesInChaos]

Using the Turkish culture this code can return false for STRINGA and stringa. It's very well possible that the OP wants that, but it's important to be aware that culture influences case insensitive comparisons

[CodesInChaos]

I'd prefer a method that explicitly specifies the culture. It's not obvious that this uses the current culture.

[CodesInChaos]

I think the results from this can still differ from using a case insensitive comparer with the same culture.

[Tudor]

Yes, this version uses the current culture according to MSDN. There is an overload with a fourth parameter that lets you specify the culture explicitly.

[Fischermaen]

If you want it to be culture invariant than use this string.Equals("stringa", "stringb", StringComparison.InvariantCultureIgnoreCase)

[CodesInChaos]

"I".ToLower()!="i".ToLower() On a Turkish system.

[Tipx]

Oh, wow. I didn't expect that! Well, I think I'll stick with my non-Turkish mindset! ;-)

[PatPeter]

What's the difference between this and StringComparison.OrdinalIgnoreCase?