diff options
Diffstat (limited to 'src/doc/book/listings/ch04-understanding-ownership/listing-04-09')
3 files changed, 48 insertions, 0 deletions
diff --git a/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.lock b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.lock new file mode 100644 index 000000000..2aa4918e5 --- /dev/null +++ b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.lock @@ -0,0 +1,6 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +[[package]] +name = "ownership" +version = "0.1.0" + diff --git a/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.toml b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.toml new file mode 100644 index 000000000..e8847526d --- /dev/null +++ b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/Cargo.toml @@ -0,0 +1,6 @@ +[package] +name = "ownership" +version = "0.1.0" +edition = "2021" + +[dependencies] diff --git a/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/src/main.rs b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/src/main.rs new file mode 100644 index 000000000..5a6ceaa1e --- /dev/null +++ b/src/doc/book/listings/ch04-understanding-ownership/listing-04-09/src/main.rs @@ -0,0 +1,36 @@ +// ANCHOR: here +fn first_word(s: &str) -> &str { + // ANCHOR_END: here + let bytes = s.as_bytes(); + + for (i, &item) in bytes.iter().enumerate() { + if item == b' ' { + return &s[0..i]; + } + } + + &s[..] +} + +// ANCHOR: usage +fn main() { + let my_string = String::from("hello world"); + + // `first_word` works on slices of `String`s, whether partial or whole + let word = first_word(&my_string[0..6]); + let word = first_word(&my_string[..]); + // `first_word` also works on references to `String`s, which are equivalent + // to whole slices of `String`s + let word = first_word(&my_string); + + let my_string_literal = "hello world"; + + // `first_word` works on slices of string literals, whether partial or whole + let word = first_word(&my_string_literal[0..6]); + let word = first_word(&my_string_literal[..]); + + // Because string literals *are* string slices already, + // this works too, without the slice syntax! + let word = first_word(my_string_literal); +} +// ANCHOR_END: usage |