Strings
Strings are used to store text.
You have already learned that you can use the &str type to create a string:
Example
let greeting: &str = "Hello";
println!("{}", greeting);Note that strings are surrounded by double quotes ( " Hello " ).
There are two main types of strings in Rust:
- &str - is called "string slices", and is used for fixed text like "Hello"
- String - used when you need a string that can change
In this chapter, you will mostly work with the String type because it is more flexible and can be changed over time.
Create a String
You can create a String from a string literal using the to_string() method or the String::from() function:
Example
let text1 = "Hello World".to_string();Example
let text2 = String::from("Hello World");It is up to you which one to choose - both to_string() and String::from() are very common in Rust.
Change a String
Strings are mutable, so you can change them if they are declared with mut .
Use push_str() to add text to a string:
Example
let mut greeting = String::from("Hello");
greeting.push_str(" World");
println!("{}", greeting); // Hello WorldExample
let mut word = String::from("Hi");
word.push('!');
println!("{}", word); // Hi!Concatenate Strings
You can combine strings using the format! macro:
Example
let s1 = String::from("Hello");
let s2 = String::from("World!");
let s3 = String::from("What a beautiful day!");
let result = format!("{} {} {}", s1, s2, s3);
println!("{}", result);You can also use the + operator to combine strings, but it can get messy with many values.
Example
let s1 = String::from("Hello");
let s2 = String::from("World!");
let s3 = String::from("What a beautiful day!");
let result = s1 + " " + &s2 + " " + &s3;
println!("{}", result);Good to know: format! is often the preferred choice than using + for combining strings.
String Length
You can use the .len() method to get the length of a string:
Example
let name = String::from("John");
println!("Length: {}", name.len()); // 4