Round Trip Format Example - Outdated code sample or no longer needed?

[BenjaminMichaelis]

Type of issue

Code doesn't work

Description

For https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings#round-trip-format-specifier-r , It shows a code example for using the round trip format specifier R on a double; however the code example has a comment at the end of the expected output. However; in my testing it has a result like this:

2 questions:

1. Is the sample code now incorrect since Update the double/float formatters to return the shortest roundtrippable string. coreclr#22040 and .ToString() by default is round-trip compatible? Maybe adbb5e9 just didn't change enough?
2. When is a necessary use for the round-trip format specifier now (maybe for some data types; but doesn't seem like it is necessary for decimal anymore).

Page URL

https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings

Content source URL

https://github.com/dotnet/docs/blob/main/docs/standard/base-types/standard-numeric-format-strings.md

Document Version Independent Id

f23035e0-f271-b48c-f9a9-8582be80b4ad

Article author

@adegeo

Metadata

• ID: 0ae38fce-fc98-9420-6b0b-ceee4e885f2d
• Service: dotnet-fundamentals

---

Associated WorkItem - 294938

[adegeo]

Hi @BenjaminMichaelis Thank you for catching this. This is indeed a change between .NET Framework and .NET. A lot of the code here in these fundamental areas were written with .NET Framework. So a note in the code results should be placed that shows the difference between the two.

[BenjaminMichaelis]

Thank you for catching this. This is indeed a change between .NET Framework and .NET. A lot of the code here in these fundamental areas were written with .NET Framework. So a note in the code results should be placed that shows the difference between the two.

Out of curiosity, when are format specifiers needed anymore? A lot of the cases seem covered by default, or they are small enough that they really are always round trip compatible. @adegeo

[adegeo]

I think a lot of that has to relate to ISO computing standards for information transmission, or business needs related to currency, security, data integrity, etc. If you need a very specific format for whatever reason, you need it. There are so many industries that have all sorts of odd requirements, whether cultural, historical, economical, or whatever. I've worked in a few where I got to see some unique processes related to data transmission and software that I never knew existed, and I've never seen used outside of that one place. 😁