Read and complete the full issue template

Do not randomly delete sections. They are here for a reason.

Do you want to request a feature or report a bug?

• Bug
• Feature
• Question

Did you test against the latest CI build?

• Yes
• No

If you answered No, please test with the latest development build first.

Version of ClosedXML

latest.

What is the current behavior?

The code is using some string operation like IndexOf without passing the StringComparison option. by default doing that the operation will assume want linguistic behavior. This can produce some surprises and wrong results in some situations. for example

Maybe will be a good idea enable the analyzers listed in https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/globalization-warnings?view=vs-2022 on your codebase.

What is the expected behavior or new feature?

The string operations in the code should always produce the desired result and be protected from surprising behaviors.

Complete this.

Is this a regression from the previous version?

No but the behavior can cause serious problems for the library users.

Reproducibility

This is an important section. Read it carefully. Failure to do so will cause a 'RTFM' comment.

Just set the current culture to Thai and run some code depends on the code path using such string operations.

Code to reproduce problem:

public void Main()
{
    CultureInfo.CurrentCulture = CultureInfo.GetCultureInfo("th-th");
    // call your library here with operation exercising the code path using such string operation
}

• I attached a sample spreadsheet. (You can drag files on to this issue)