问题
How does String::from("") & "".to_string() differ in Rust?
Is there any difference in stack and heap allocation in both cases?
回答1:
How does
String::from("")&"".to_string()differ in Rust?
They're part of different protocols (traits): std::convert::From and alloc::string::ToString[0].
However, when it comes to &str/String they do the same thing (as does "".to_owned()).
Is there any difference in stack and heap allocation in both cases?
As joelb's link indicates, before Rust 1.19 "".to_string() was markedly slower than the alternatives as it went through the entire string formatting machinery. That's no longer the case.
[0] ToString is also automatically implemented if the structure implements Display[1]
[1] functionally s.to_string() is equivalent to format!("{}", s), it's usually recommended to not implement ToString directly, unless bypassing the formatting machinery can provide significant performance improvements (which is why str/String do it)
来源：https://stackoverflow.com/questions/61475158/how-does-stringfrom-to-string-differ-in-rust