There are two types of strings in Rust: String
and &str
.
A String
is stored as a vector of bytes (Vec<u8>
), but guaranteed to
always be a valid UTF-8 sequence. String
is heap allocated, growable and not
null terminated.
&str
is a slice (&[u8]
) that always points to a valid UTF-8 sequence, and
can be used to view into a String
, just like &[T]
is a view into Vec<T>
.
fn main() { // (all the type annotations are superfluous) // A reference to a string allocated in read only memory let pangram: &'static str = "the quick brown fox jumps over the lazy dog"; println!("Pangram: {}", pangram); // Iterate over words in reverse, no new string is allocated println!("Words in reverse"); for word in pangram.split_whitespace().rev() { println!("> {}", word); } // Copy chars into a vector, sort and remove duplicates let mut chars: Vec<char> = pangram.chars().collect(); chars.sort(); chars.dedup(); // Create an empty and growable `String` let mut string = String::new(); for c in chars { // Insert a char at the end of string string.push(c); // Insert a string at the end of string string.push_str(", "); } // The trimmed string is a slice to the original string, hence no new // allocation is performed let chars_to_trim: &[char] = &[' ', ',']; let trimmed_str: &str = string.trim_matches(chars_to_trim); println!("Used characters: {}", trimmed_str); // Heap allocate a string let alice = String::from("I like dogs"); // Allocate new memory and store the modified string there let bob: String = alice.replace("dog", "cat"); println!("Alice says: {}", alice); println!("Bob says: {}", bob); }
More str
/String
methods can be found under the
std::str and
std::string
modules