X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/7b5af93d756464638204b0b703485712d88d3656..a2eeb1b93e8f52b2119fb11d56f5ffc764ac747b:/src/part03.rs?ds=sidebyside diff --git a/src/part03.rs b/src/part03.rs index d8d71b1..ef8ab92 100644 --- a/src/part03.rs +++ b/src/part03.rs @@ -22,13 +22,13 @@ use std::io; //@ specifying its type parameter doesn't tell us all that much. fn read_vec() -> Vec { let mut vec: Vec = Vec::::new(); - // The central handle to the standard input is made available by `io::stdin()`. + // The central handle to the standard input is made available by the function `io::stdin`. let stdin = io::stdin(); println!("Enter a list of numbers, one per line. End with Ctrl-D."); //@ We would now like to iterate over standard input line-by-line. We can use a `for` loop //@ for that, but there is a catch: What happens if there is some other piece of code running //@ concurrently, that also reads from standard input? The result would be a mess. Hence - //@ Rust requires us to `lock()` standard input if we want to perform large operations on + //@ Rust requires us to `lock` standard input if we want to perform large operations on //@ it. (See [the documentation](http://doc.rust-lang.org/stable/std/io/struct.Stdin.html) for more //@ details.) for line in stdin.lock().lines() { @@ -40,17 +40,17 @@ fn read_vec() -> Vec { //@ You will see that `io::Result` is actually just an alias for `Result`, so click on that to obtain //@ the list of all constructors and methods of the type. - //@ We will be lazy here and just assume that nothing goes wrong: `unwrap()` returns the `String` if there is one, + //@ We will be lazy here and just assume that nothing goes wrong: `unwrap` returns the `String` if there is one, //@ and panics the program otherwise. Since a `Result` carries some details about the error that occurred, //@ there will be a somewhat reasonable error message. Still, you would not want a user to see such //@ an error, so in a "real" program, we would have to do proper error handling. - //@ Can you find the documentation of `Result::unwrap()`? + //@ Can you find the documentation of `Result::unwrap`? //@ // I chose the same name (`line`) for the new variable to ensure that I will never, accidentally, // access the "old" `line` again. let line = line.unwrap(); // Now that we have our `String`, we want to make it an `i32`. - //@ We first `trim()` the `line` to remove leading and trailing whitespace. + //@ We first `trim` the `line` to remove leading and trailing whitespace. //@ `parse` is a method on `String` that can convert a string to anything. Try finding it's documentation! //@ In this case, Rust *could* figure out automatically that we need an `i32` (because of the return type @@ -61,7 +61,7 @@ fn read_vec() -> Vec { //@ something that is not a number). //@ This is a common pattern in Rust: Operations that could go wrong will return `Option` or `Result`. //@ The only way to get to the value we are interested in is through pattern matching (and through helper functions - //@ like `unwrap()`). If we call a function that returns a `Result`, and throw the return value away, + //@ like `unwrap`). If we call a function that returns a `Result`, and throw the return value away, //@ the compiler will emit a warning. It is hence impossible for us to *forget* handling an error, //@ or to accidentally use a value that doesn't make any sense because there was an error producing it. Ok(num) => {