Strings

String Types in Rust

Rust has two string types:

String

• Growable, heap-allocated
• UTF-8 encoded
• Owned type

&str

• Fixed-size string slice
• UTF-8 encoded
• Reference type

Creating Strings

// String
let s1 = String::from("hello");
let s2 = "hello".to_string();

// &str
let s3 = "hello";

String Operations

Concatenation

let s1 = String::from("Hello, ");
let s2 = String::from("world!");
let s3 = s1 + &s2;  // s1 has been moved and can no longer be used

Appending

let mut s = String::from("hello");
s.push_str(", world!");
s.push('!');

String Slices

let s = String::from("hello world");
let hello = &s[0..5];
let world = &s[6..11];

UTF-8 Encoding

let s = String::from("नमस्ते");
for c in s.chars() {
    println!("{}", c);
}

Comparing to JavaScript

JavaScript has a single string type:

let s1 = "hello";
let s2 = new String("hello");

String Methods

Length

let s = String::from("hello");
let len = s.len();  // 5

Contains

let s = String::from("hello world");
let contains = s.contains("world");  // true

Replace

let s = String::from("hello world");
let s2 = s.replace("world", "rust");

String Formatting

let name = "Alice";
let age = 30;
let s = format!("{} is {} years old", name, age);

Conclusion

Rust’s string system provides safety and performance through its two string types.