wiki/content/20200915151358-strings.md

---
date: 2020-09-15
id: 490f0710-971d-4150-a339-4a8c2f5d19a8
title: Rust Strings
---

# Description

The `String` type, which is provided by Rust’s standard library rather
than coded into the core language, is a growable, mutable, owned, UTF-8
encoded string type. When Rustaceans refer to “strings” in Rust, they
usually mean the `String` and the string slice `&str` types, not just
one of those types. Although this section is largely about `String`,
both types are used heavily in Rust’s standard library, and both
`String` and string slices are UTF-8 encoded.

# Creating a New String

Many [Vector operations](20200915140449-vectors) are also available for
Strings.

``` rust
fn main() {
    let mut s = String::new();
}
```

## to~string~

To generate a `String` with initial data we can use the
[to~string~](https://doc.rust-lang.org/std/string/trait.ToString.html#tymethod.to_string)
method:

``` rust
fn main() {
    let data = "initial contents";

    let s = data.to_string();

    // the method also works on a literal directly:
    let s = "initial contents".to_string();
}
```

## String::from

The same can be accomplished with `String::from`:

``` rust
fn main() {
    let s = String::from("initial contents");
}
```

# Updating a String

## push~str~

``` rust
fn main() {
    let mut s = String::from("foo");
    s.push_str("bar");

    println!("s is {}", s)
}
```

## push

`push` adds a single character to a string:

``` rust
fn main() {
    let mut s = String::from("lo");
    s.push('l');

    println!("s is {}", s)
}
```

# Concatentation

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

    println!("s3 is {}", s3)
}
```

## Concatenate multiple strings

### With +

``` rust
fn main() {
    let s1 = String::from("tic");
    let s2 = String::from("tac");
    let s3 = String::from("toe");

    let s = s1 + "-" + &s2 + "-" + &s3;

    println!("s is {}", s)
}
```

### With format!

``` rust
fn main() {
    let s1 = String::from("tic");
    let s2 = String::from("tac");
    let s3 = String::from("toe");

    let s = format!("{}-{}-{}", s1, s2, s3);

    println!("s is {}", s)
}
```

# Iteration

## Chars

``` rust
#![allow(unused)]
fn main() {
    for c in "नमस्ते".chars() {
        println!("{}", c);
    }
}
```

## Bytes

``` rust
#![allow(unused)]
fn main() {
    for b in "नमस्ते".bytes() {
        println!("{}", b);
    }
}
```