.net 5.0 seems to be wrong in detecting zero-terminzted string

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work] [regression] [worked-in:16.7]
The following code:

     class Program
     {
         static void Main(string[] args)
         {
             const string s = "abc";
             const string sz = "abc\0";
    
void Report(string str) 
                 => Console.WriteLine($"\"{str}\" ({str. Length}), zero-terminated: {str. EndsWith("\0")}");
    
Report(s);
             Report(sz);
         }
     }

gives the following output for target framework .net 5.0:

"abc" (3), zero-terminated: True
"abc" (4), zero-terminated: True

For target framework .netcoreapp3.1 the code outputs the following lines:

"abc" (3), zero-terminated: False
"abc" (4), zero-terminated: True

As for me, .net core 3.1 behavior looks correct and .net 5.0 does not.

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Original Comments

Feedback Bot on 12/9/2020, 10:13 PM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

---

Original Solutions

(no solutions)

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[danmoseley]

@safern, the repro goes away if I set DOTNET_SYSTEM_GLOBALIZATION_USENLS=1

Did we discuss this case already?

Tagging subscribers to this area: @tarekgh, @safern, @krwq
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Issue Details

---

This issue has been moved from a ticket on Developer Community.

---

[severity:It's more difficult to complete my work] [regression] [worked-in:16.7]
The following code:

     class Program
     {
         static void Main(string[] args)
         {
             const string s = "abc";
             const string sz = "abc\0";
    
void Report(string str) 
                 => Console.WriteLine($"\"{str}\" ({str. Length}), zero-terminated: {str. EndsWith("\0")}");
    
Report(s);
             Report(sz);
         }
     }

gives the following output for target framework .net 5.0:

"abc" (3), zero-terminated: True
"abc" (4), zero-terminated: True

For target framework .netcoreapp3.1 the code outputs the following lines:

"abc" (3), zero-terminated: False
"abc" (4), zero-terminated: True

As for me, .net core 3.1 behavior looks correct and .net 5.0 does not.

---

Original Comments

Feedback Bot on 12/9/2020, 10:13 PM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

---

Original Solutions

(no solutions)

Author:	vsfeedback
Assignees:	-
Labels:	area-System.Globalization, area-System.Runtime, untriaged
Milestone:	-

[GrabYourPitchforks]

This behavior is by design. EndsWith(string) is linguistic (culture-aware), and the null character has zero weight under ICU. Caller almost certainly meant to perform an ordinal comparison via EndsWith(char) or EndsWith(..., StringComparison.Ordinal).

[safern]

Thanks, @GrabYourPitchforks you beat me to it.

[tarekgh]

@GrabYourPitchforks is right. For such operation ordinal comparison has to be used. Also why need to use EndsWith at all? why not just testing str[str.Length - 1] == `\0' ?

[GrabYourPitchforks]

To be fair, EndsWith is more readable. And it works with empty strings. :)

[tarekgh]

To be fair, EndsWith is more readable. And it works with empty strings. :)

That is a good point. but do you consider the empty string is null terminated or not? for such user scenarios, it should be true I guess.