Strings و&str

نوعا String

fn main() {
    let owned: String = String::from("hello");
    let borrowed: &str = "world";
    println!("{} {}", owned, borrowed);
}

ثوابت السلاسل النصية هي &str

fn main() {
    let greeting = "Hi there"; // type is &str
    println!("{}", greeting);
}

إنشاء String

fn main() {
    let a = String::from("abc");
    let b = "xyz".to_string();
    println!("{} {}", a, b);
}

زيادة حجم String

fn main() {
    let mut s = String::from("Hello");
    s.push_str(", ");
    s.push_str("Rust");
    s.push('!');
    println!("{}", s);
}

الضم

fn main() {
    let first = String::from("Hello");
    let second = String::from("World");
    let joined = format!("{} {}", first, second);
    println!("{}", joined);
}

استعارة String كـ &str

fn print_text(text: &str) {
    println!("text: {}", text);
}

fn main() {
    let owned = String::from("owned");
    print_text(&owned);
    print_text("literal");
}

لماذا نفضّل معاملات &str

fn shout(s: &str) -> String {
    s.to_uppercase()
}

fn main() {
    println!("{}", shout("quiet"));
}

الطول بالبايتات

fn main() {
    let s = "hello";
    println!("{} bytes", s.len());
}

التحقق من المحتوى

fn main() {
    let s = "hello world";
    println!("{}", s.contains("world"));
    println!("{}", s.starts_with("hello"));
}

اختلاف الملكية

fn main() {
    let owned = String::from("data");
    let view: &str = &owned[0..2];
    println!("owned {} view {}", owned, view);
}

التحويل بينهما

fn main() {
    let s = String::from("convert");
    let slice: &str = s.as_str();
    let back: String = slice.to_string();
    println!("{} {}", slice, back);
}

تحقق سريع

مراجعة

fn main() {
    let mut msg = String::from("Rust");
    msg.push_str(" rocks");
    let view: &str = &msg;
    println!("{} ({} bytes)", view, view.len());
}