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

[regression] [worked-in:.net core 3.1]
Using .NET 5 IndexOf(string) returns wrong index.
This is reproducible only for some input strings, when the culture is set to Thai.

Example:
CultureInfo.CurrentCulture = new CultureInfo("th");
var idxSeparator = "27".IndexOf("."); // returns 0 instead of -1
idxSeparator = "0".IndexOf("."); // returns -1 as expected
idxSeparator = "3".IndexOf("."); // returns -1 as expected
idxSeparator = "3345".IndexOf("."); // returns 0 instead of -1

Notes

• in .netcore3.1 it returned -1 for all examples above (as I would expect)
• In other languages this is not reproducible also in .Net 5
• Indexof(char) does not have this problem

Original Comments

Feedback Bot on 9/7/2021, 01:21 AM:

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)