System.IO -> file.name ... UTF8-problem?

Hi folks,

maybe a silly question...

For example I'm using

foreach(FileInfo file in fi.GetFiles()){
...some code
}

Then I get the name of the file in file.name .

Lets asume the filename is something with ä,ö,ü, for example file.name is zündhölzer.jpg

When I now search in this filename like this:

string sourceString = file.name; (file.name is zündhölzer.jpg)
string searchString = "zündhölzer.jpg"

if (sourceString.Contains(searchString)) {

....
}

...will not work. It doesnt find the searchString, even if sourceString and searchString are equal. This is only the case, when the searchString comes from a file.info, so I asume the probleme has something to do with encoding in the System.IO ??

Best regards
Jörg

 

https://msdn.microsoft.com/en-us/library/cc190529(v=vs.110).aspx

Code (CSharp):

1.         string fileName = System.IO.Path.GetFileName(file.FullName);
2.         int test = String.Compare(fileName, searchString, StringComparison.OrdinalIgnoreCase);
3.         if(test == 0){
4.             // your code
5.         }

 

What they said ^

You wont be able to use StringComparison with Contains but you can use IndexOf for the same effect.

 

Wow... that was fast. Thank you both.

Finally you pushed me into the right direction. I now use

int found = sourceString.IndexOf(searchString, System.StringComparison.InvariantCulture);

 

You will bump into problems using IndexOf like that with the InvariantCulture. Here is an extension method that will return a bool for you and will properly us String.Compare

Code (CSharp):

1.  
2. public static class Extensions{
3.  
4.     public static bool IsCultureInvariantMatch(this string val, string check){
5.         int test = String.Compare(val, check, StringComparison.OrdinalIgnoreCase);
6.         return test == 0;
7.     }
8.  
9.     public static bool IsFileNameMatch(this System.IO.FileInfo info, string check){
10.         return info.FullName.IsCultureInvariantMatch(check);
11.     }
12.  
13. }
14.  

here is a usage example, obviously you would use your variables and not hard coded strings;

Code (CSharp):

1.  
2. // file is supposed to be your FileInfo object in your loop
3. Console.WriteLine(file.IsFileNameMatch("zündhölzer.jpg"));
4. Console.WriteLine("zündhölzer.jpg".IsCultureInvariantMatch("zündhölzer.jpg"));
5.  

and here is a DotNetFiddle for you demonstrating how it works:
https://dotnetfiddle.net/XIXT7C


Sidenote: It is very important in your case to use OrdinalIgnoreCase, ordinal aspect of that is what will match your file names consistently. read more about that here: https://msdn.microsoft.com/en-us/library/system.stringcomparer.ordinalignorecase(v=vs.110).aspx

 

Thank you very much.

My problem is, I dont need no check if the strings match exactly (like in the string.compare-example) but some kind of search inside the string, for example: is "ündhö" part of the string "zündhölzer", one could call it a "full text search". So for this purpose it seemed to me that the indexOf ist the right solution (and at the moment it works perfectly fine), whenever it gives back a value bigger than -1, the search-string is somewhere part of the source-string, and thats all I wanna know. However I will study your links, to dive deeper into this stuff. It's not my domain at the moment, all the file/search stuff is part of the not-so-fancy-stuff in my software... ;-)

 

OK, that makes more sense. you should still use OrdinalIgnoreCase instead of just CultureInvariant

 

Ok, I'll do that. Many thanks for your fast, friendly and competent responses!