ftell() not consistent in C11

[damorinCan]

Some legacy tools stopped suddenly working after 20+ years.

https://stackoverflow.com/questions/79762122/ftell-no-more-returning-the-correct-offset-on-a-text-file-with-windows-11-ente

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[chrchr-github]

Thanks for your contribution.
As far as I can tell, this has nothing to do with Windows 11, but rather the C11 spec of ftell(), right? So the title of the PR should be adjusted.
Please add a test.

[damorinCan]

So the title of the PR should be adjusted.

Title now including reference to C11 and removed reference to Windows 11.

Please add a test.

I added a test in test/testio.cpp. Anything missing in it ?

[chrchr-github]

Please add a test.

I added a test in test/testio.cpp. Anything missing in it ?

Thanks, I must have missed that.