54 lines
1.8 KiB
Rust
54 lines
1.8 KiB
Rust
fn main() {
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let s = String::from("hello"); // s comes into scope
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takes_ownership(s); // s's value moves into the function...
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// ... and so is no longer valid here
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let x = 5; // x comes into scope
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makes_copy(x); // x would move into the function,
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// but i32 is Copy, so it’s okay to still
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// use x afterward
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let s1 = gives_ownership(); // gives_ownership moves its return
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// value into s1
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let s2 = String::from("hello"); // s2 comes into scope
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let s3 = takes_and_gives_back(s2); // s2 is moved into
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// takes_and_gives_back, which also
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// moves its return value into s3
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} // Here, s3 goes out of scope and is dropped. s2 goes out of scope but was
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// moved, so nothing happens. s1 goes out of scope and is dropped.
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// Here, x goes out of scope, then s. But because s's value was moved, nothing
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// special happens.
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fn takes_ownership(some_string: String) { // some_string comes into scope
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println!("{}", some_string);
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} // Here, some_string goes out of scope and `drop` is called. The backing
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// memory is freed.
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fn makes_copy(some_integer: i32) { // some_integer comes into scope
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println!("{}", some_integer);
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} // Here, some_integer goes out of scope. Nothing special happens.
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fn gives_ownership() -> String { // gives_ownership will move its
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// return value into the function
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// that calls it
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let some_string = String::from("hello"); // some_string comes into scope
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some_string // some_string is returned and
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// moves out to the calling
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// function
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}
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// takes_and_gives_back will take a String and return one
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fn takes_and_gives_back(a_string: String) -> String { // a_string comes into
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// scope
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a_string // a_string is returned and moves out to the calling function
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}
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