Rust String

In Rust, a String is a growable collection of characters stored in heap-allocated memory. Strings are similar to vectors, but they contain Unicode characters instead of bytes, and they have additional methods for manipulating and working with strings.

Here's an example of how to create and use a String in Rust:

fn main() {
    let mut s = String::from("hello");  // create a new String with the value "hello"
    s.push_str(", world!");  // append ", world!" to the String

    println!("{}", s);  // prints "hello, world!"
    println!("Length: {}", s.len());  // prints "Length: 13"
    println!("Capacity: {}", s.capacity());  // prints "Capacity: 22"
}

In this example, we're creating a new String called s with the value "hello" using the String::from constructor. We're then appending ", world!" to the end of the string using the push_str method. We're printing the value of the string using the println! macro, as well as its length and capacity using the len and capacity methods.

One important thing to note about Strings in Rust is that they are UTF-8 encoded by default, which means they can contain any Unicode character. Rust's string handling functions are designed to handle Unicode characters and avoid common issues with non-ASCII characters, such as buffer overflows or invalid encoding.

Here's an example of how to iterate over the characters in a String:

fn main() {
    let s = String::from("hello");

    for c in s.chars() {
        println!("{}", c);  // prints each character of the string on a separate line
    }
}

In this example, we're creating a new String called s with the value "hello". We're then iterating over the characters in the string using the chars method and printing each character on a separate line using the println! macro.

You can also convert a String to a &str (a string slice) using the as_str method:

fn main() {
    let s = String::from("hello");
    let slice = s.as_str();

    println!("{}", slice);  // prints "hello"
}

In this example, we're creating a new String called s with the value "hello". We're then converting the String to a string slice using the as_str method and storing it in a variable called slice. Finally, we're printing the value of the string slice using the println! macro.