Rustの文字列操作｜便利なメソッドと使い方

let mut s = String::from("hello");
s.push_str(", world!");
println!("{}", s); // Output: hello, world!

// 文字列リテラルからString型を作成
let s1 = String::from("hello");
let s2 = "world".to_string();

// &strからStringへの変換
let s3: &str = "example";
let s4 = s3.to_string();
let s5 = String::from(s3);

let num = 123;
let num_str = num.to_string();
println!("{}", num_str); // Output: 123

let name = "Alice";
let age = 30;
let message = format!("My name is {} and I am {} years old.", name, age);
println!("{}", message); // Output: My name is Alice and I am 30 years old.

let s = String::from("hello");
let len = s.len();
println!("{}", len); // Output: 5

let s = String::from("");
let is_empty = s.is_empty();
println!("{}", is_empty); // Output: true

let s = String::from("hello,world");
for part in s.split(',') {
    println!("{}", part);
}
// Output:
// hello
// world

let s = String::from("  hello  ");
let trimmed = s.trim();
println!("{}", trimmed); // Output: hello

let s = String::from("hello world");
let replaced = s.replace("world", "Rust");
println!("{}", replaced); // Output: hello Rust

let s = String::from("Hello");
let uppercase = s.to_uppercase();
let lowercase = s.to_lowercase();
println!("{}", uppercase); // Output: HELLO
println!("{}", lowercase); // Output: hello

let s1 = String::from("hello");
let s2 = String::from("hello");
let s3 = String::from("world");

println!("{}", s1 == s2); // Output: true
println!("{}", s1 == s3); // Output: false

use std::cmp::Ordering;

let s1 = String::from("apple");
let s2 = String::from("banana");

match s1.cmp(&s2) {
    Ordering::Less => println!("apple is less than banana"),
    Ordering::Equal => println!("apple is equal to banana"),
    Ordering::Greater => println!("apple is greater than banana"),
}