String in Rust

Slice

A string slice is a reference to part of a String.

let s = String::from("hello world");

let hello = &s[0..5];//hello
let world = &s[6..11];//world

Here, s is an immutable string slice.

let s:&'static str = "Hello, world!";//data type is &'static str
let my_string:String = s.to_string()//data type is String

Slice examples:

let my_string = String::from("hello world");
&my_string[..]//string slice
let my_string_literal = "hello world";
my_string_literal//string slice
my_string_literal[..]//string slice

String

Rust core supports only one string type: the string slice, str.

You usually see it in the form &str.

String is a type provided by Rust's standard library.

Rust's standard library also provides string-related types such as OsString, OsStr, CString, and CStr.

Creating a new String

1.
let data = "initial contents";
let s = data.to_string();

2.
let s = "initial contents".to_string();

3.
let s = String::from("initial contents");

Updating a String

1.
let mut s = String::from("foo");
s.push_str("bar");

2.
let mut s1 = String::from("foo");
let s2 = "bar";
s1.push_str(s2);

3.
let mut s = String::from("lo");
s.push('l');

Concatenating Strings

In this example, s1 can no longer be used afterward. Also, when creating s3, s2 must have & in front of it so it becomes an &String.

let s1 = String::from("Hello, ");
let s2 = String::from("world!");
let s3 = s1 + &s2;

Actually, + is replaced with a function called add().

s1.add(s2)

It has this shape. Take a quick look at the signature of add().

fn add(self, s: &str) -> String {

It receives an argument of type s: &str. Since &String is coerced to &str, we do not need to worry about it here.

Indexing

The following code produces an error because Rust strings do not support indexing.

let s1 = String::from("hello");
let h = s1[0];

UTF-8

let hello = String::from("Hola");// 4bytes
let hello = String::from("Здравствуйте");//12 characters but 24 bytes
let hello = "Здравствуйте";
for n in hello.as_bytes(){
    println!("{}",n);

}

This prints 6 chars.

for c in "नमस्ते".chars() {
    println!("{}", c);
}

This prints 18 bytes.

for b in "नमस्ते".bytes() {
    println!("{}", b);
}