Skip to content

Improve the hints in fmt (1.2.3. Formatting); mention type casting #1951

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Aug 13, 2025
Merged

Improve the hints in fmt (1.2.3. Formatting); mention type casting #1951

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 10 additions & 4 deletions src/hello/print/fmt.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -78,13 +78,18 @@ RGB (0, 3, 254) 0x0003FE
RGB (0, 0, 0) 0x000000
```

Three hints if you get stuck:
Two hints if you get stuck:

* The formula for calculating a color in the RGB color space is:
`RGB = (R*65536)+(G*256)+B , (when R is RED, G is GREEN and B is BLUE)`.
For more see [RGB color format & calculation][rgb_color].
* You [may need to list each color more than once][named_parameters].
* You can [pad with zeros to a width of 2][fmt_width] with `:0>2`.
For hexadecimals, you can use `:02X`.

Bonus:

* If you would like to experiment with [type casting][type_casting] in advance,
the formula for [calculating a color in the RGB color space][rgb_color] is
`RGB = (R * 65_536) + (G * 256) + B`, where `R is RED, G is GREEN, and B is BLUE`.
An unsigned 8-bit integer (`u8`) can only hold numbers up to 255. To cast `u8` to `u32`, you can write `variable_name as u32`.

### See also:

Expand All @@ -96,3 +101,4 @@ For more see [RGB color format & calculation][rgb_color].
[fmt]: https://doc.rust-lang.org/std/fmt/
[fmt_traits]: https://doc.rust-lang.org/std/fmt/#formatting-traits
[fmt_width]: https://doc.rust-lang.org/std/fmt/#width
[type_casting]: ../../types/cast.md