From 059c1bc872dd9c94fa231dfd19813cc59f06f7d6 Mon Sep 17 00:00:00 2001 From: Robert Zhao Date: Sun, 11 Jun 2023 19:45:48 -0400 Subject: [PATCH] Complete errors exercises --- exercises/error_handling/errors1.rs | 8 +++----- exercises/error_handling/errors2.rs | 5 +---- exercises/error_handling/errors3.rs | 6 +++--- exercises/error_handling/errors4.rs | 11 +++++++---- exercises/error_handling/errors5.rs | 17 +++++++---------- exercises/error_handling/errors6.rs | 16 ++++++++-------- 6 files changed, 29 insertions(+), 34 deletions(-) diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs index bcee9723..6bfe94a0 100644 --- a/exercises/error_handling/errors1.rs +++ b/exercises/error_handling/errors1.rs @@ -5,14 +5,12 @@ // construct to `Option` that can be used to express error conditions. Let's use it! // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE - -pub fn generate_nametag_text(name: String) -> Option { +pub fn generate_nametag_text(name: String) -> Result { if name.is_empty() { // Empty names aren't allowed. - None + Err("`name` was empty; it must be nonempty.".into()) } else { - Some(format!("Hi! My name is {}", name)) + Ok(format!("Hi! My name is {}", name)) } } diff --git a/exercises/error_handling/errors2.rs b/exercises/error_handling/errors2.rs index 6971fcfb..f4423dba 100644 --- a/exercises/error_handling/errors2.rs +++ b/exercises/error_handling/errors2.rs @@ -17,15 +17,12 @@ // one is a lot shorter! // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE - use std::num::ParseIntError; pub fn total_cost(item_quantity: &str) -> Result { let processing_fee = 1; let cost_per_item = 5; - let qty = item_quantity.parse::(); - + let qty = item_quantity.parse::()?; Ok(qty * cost_per_item + processing_fee) } diff --git a/exercises/error_handling/errors3.rs b/exercises/error_handling/errors3.rs index a2d2d190..9b30f083 100644 --- a/exercises/error_handling/errors3.rs +++ b/exercises/error_handling/errors3.rs @@ -4,11 +4,9 @@ // Why not? What should we do to fix it? // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE - use std::num::ParseIntError; -fn main() { +fn main() -> Result<(), ParseIntError> { let mut tokens = 100; let pretend_user_input = "8"; @@ -16,9 +14,11 @@ fn main() { if cost > tokens { println!("You can't afford that many!"); + Ok(()) } else { tokens -= cost; println!("You now have {} tokens.", tokens); + Ok(()) } } diff --git a/exercises/error_handling/errors4.rs b/exercises/error_handling/errors4.rs index 0efe8ccd..3fe49c84 100644 --- a/exercises/error_handling/errors4.rs +++ b/exercises/error_handling/errors4.rs @@ -1,8 +1,6 @@ // errors4.rs // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE - #[derive(PartialEq, Debug)] struct PositiveNonzeroInteger(u64); @@ -14,8 +12,13 @@ enum CreationError { impl PositiveNonzeroInteger { fn new(value: i64) -> Result { - // Hmm...? Why is this only returning an Ok value? - Ok(PositiveNonzeroInteger(value as u64)) + if value > 0 { + Ok(PositiveNonzeroInteger(value as u64)) + } else if value < 0 { + Err(CreationError::Negative) + } else { + Err(CreationError::Zero) + } } } diff --git a/exercises/error_handling/errors5.rs b/exercises/error_handling/errors5.rs index eb5506cb..ebddefeb 100644 --- a/exercises/error_handling/errors5.rs +++ b/exercises/error_handling/errors5.rs @@ -16,14 +16,11 @@ // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE +use std::error::Error; +use std::fmt::Result as FmtResult; +use std::fmt::{Display, Formatter}; -use std::error; -use std::fmt; -use std::num::ParseIntError; - -// TODO: update the return type of `main()` to make this compile. -fn main() -> Result<(), Box> { +fn main() -> Result<(), Box> { let pretend_user_input = "42"; let x: i64 = pretend_user_input.parse()?; println!("output={:?}", PositiveNonzeroInteger::new(x)?); @@ -52,8 +49,8 @@ impl PositiveNonzeroInteger { } // This is required so that `CreationError` can implement `error::Error`. -impl fmt::Display for CreationError { - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { +impl Display for CreationError { + fn fmt(&self, f: &mut Formatter) -> FmtResult { let description = match *self { CreationError::Negative => "number is negative", CreationError::Zero => "number is zero", @@ -62,4 +59,4 @@ impl fmt::Display for CreationError { } } -impl error::Error for CreationError {} +impl Error for CreationError {} diff --git a/exercises/error_handling/errors6.rs b/exercises/error_handling/errors6.rs index 8097b490..194d38a5 100644 --- a/exercises/error_handling/errors6.rs +++ b/exercises/error_handling/errors6.rs @@ -8,8 +8,6 @@ // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a hint. -// I AM NOT DONE - use std::num::ParseIntError; // This is a custom error type that we will be using in `parse_pos_nonzero()`. @@ -23,15 +21,17 @@ impl ParsePosNonzeroError { fn from_creation(err: CreationError) -> ParsePosNonzeroError { ParsePosNonzeroError::Creation(err) } - // TODO: add another error conversion function here. - // fn from_parseint... + + fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError { + ParsePosNonzeroError::ParseInt(err) + } } fn parse_pos_nonzero(s: &str) -> Result { - // TODO: change this to return an appropriate error instead of panicking - // when `parse()` returns an error. - let x: i64 = s.parse().unwrap(); - PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation) + match s.parse() { + Ok(v) => PositiveNonzeroInteger::new(v).map_err(ParsePosNonzeroError::from_creation), + Err(parse_int_error) => Err(ParsePosNonzeroError::from_parseint(parse_int_error)), + } } // Don't change anything below this line.