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145 lines
2.5 KiB
Markdown
145 lines
2.5 KiB
Markdown
---
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date: 20200915
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id: 490f0710-971d-4150-a339-4a8c2f5d19a8
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title: Rust Strings
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---
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# Description
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The `String` type, which is provided by Rust’s standard library rather
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than coded into the core language, is a growable, mutable, owned, UTF-8
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encoded string type. When Rustaceans refer to “strings” in Rust, they
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usually mean the `String` and the string slice `&str` types, not just
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one of those types. Although this section is largely about `String`,
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both types are used heavily in Rust’s standard library, and both
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`String` and string slices are UTF-8 encoded.
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# Creating a New String
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Many [Vector operations](20200915140449-vectors) are also available for
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Strings.
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``` rust
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fn main() {
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let mut s = String::new();
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}
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```
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## to~string~
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To generate a `String` with initial data we can use the
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[to~string~](https://doc.rust-lang.org/std/string/trait.ToString.html#tymethod.to_string)
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method:
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``` rust
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fn main() {
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let data = "initial contents";
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let s = data.to_string();
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// the method also works on a literal directly:
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let s = "initial contents".to_string();
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}
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```
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## String::from
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The same can be accomplished with `String::from`:
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``` rust
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fn main() {
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let s = String::from("initial contents");
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}
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```
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# Updating a String
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## push~str~
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``` rust
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fn main() {
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let mut s = String::from("foo");
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s.push_str("bar");
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println!("s is {}", s)
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}
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```
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## push
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`push` adds a single character to a string:
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``` rust
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fn main() {
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let mut s = String::from("lo");
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s.push('l');
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println!("s is {}", s)
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}
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```
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# Concatentation
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``` rust
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fn main() {
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let s1 = String::from("Hello, ");
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let s2 = String::from("world!");
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let s3 = s1 + &s2; // note s1 has been moved here and can no longer be used
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println!("s3 is {}", s3)
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}
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```
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## Concatenate multiple strings
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### With +
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``` rust
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fn main() {
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let s1 = String::from("tic");
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let s2 = String::from("tac");
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let s3 = String::from("toe");
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let s = s1 + "-" + &s2 + "-" + &s3;
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println!("s is {}", s)
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}
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```
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### With format!
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``` rust
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fn main() {
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let s1 = String::from("tic");
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let s2 = String::from("tac");
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let s3 = String::from("toe");
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let s = format!("{}-{}-{}", s1, s2, s3);
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println!("s is {}", s)
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}
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```
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# Iteration
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## Chars
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``` rust
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#![allow(unused)]
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fn main() {
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for c in "नमस्ते".chars() {
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println!("{}", c);
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}
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}
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```
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## Bytes
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``` rust
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#![allow(unused)]
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fn main() {
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for b in "नमस्ते".bytes() {
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println!("{}", b);
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}
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}
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```
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