macro_rules! format {
($($arg:tt)*) => { ... };
}Creates a String using interpolation of runtime expressions.
The first argument format! receives is a format string. This must be a string literal. The power of the formatting string is in the {}s contained. Additional parameters passed to format! replace the {}s within the formatting string in the order given unless named or positional parameters are used.
See the formatting syntax documentation in std::fmt for details.
A common use for format! is concatenation and interpolation of strings. The same convention is used with print! and write! macros, depending on the intended destination of the string; all these macros internally use format_args!.
To convert a single value to a string, use the to_string method. This will use the Display formatting trait.
To concatenate literals into a &'static str, use the concat! macro.
format! panics if a formatting trait implementation returns an error. This indicates an incorrect implementation since fmt::Write for String never returns an error itself.
format!("test"); format!("hello {}", "world!"); format!("x = {}, y = {val}", 10, val = 30); let (x, y) = (1, 2);
format!("{x} + {y} = 3"); RetroSearch is an open source project built by @garambo | Open a GitHub Issue
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