diff options
| -rw-r--r-- | src/libcollections/fmt.rs | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/src/libcollections/fmt.rs b/src/libcollections/fmt.rs index fbd07e48a84..d2abb59ffab 100644 --- a/src/libcollections/fmt.rs +++ b/src/libcollections/fmt.rs @@ -105,11 +105,18 @@ //! hexadecimal as well as an //! octal. //! -//! There are various parameters which do require a particular type, however. -//! Namely if the syntax `{:.*}` is used, then the number of characters to print -//! precedes the actual object being formatted, and the number of characters -//! must have the type `usize`. Although a `usize` can be printed with `{}`, it is -//! illegal to reference an argument as such. For example this is another +//! There are various parameters which do require a particular type, however. Namely, the `{:.*}` +//! syntax, which sets the number of numbers after the decimal in floating-point types: +//! +//! ``` +//! let formatted_number = format!("{:.*}", 2, 1.234567); +//! +//! assert_eq!("1.23", formatted_number) +//! ``` +//! +//! If this syntax is used, then the number of characters to print precedes the actual object being +//! formatted, and the number of characters must have the type `usize`. Although a `usize` can be +//! printed with `{}`, it is illegal to reference an argument as such. For example this is another //! invalid format string: //! //! ```text |