fixed iterator1 exercise by giving the compiler less clues
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@ -1,9 +1,10 @@
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// 1. Complete the divide function
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// 2. Uncomment and complete the second part of the main function
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// For part 2 there is a minor hint around line 100 and a major hint around line 128
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// There is a minor side quest in the "print_result_with_list" function
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// There are some final comments for when you are done around line 150
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// Have fun :-)
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// In production code you would not derive Debug, but implement it manually to get a better error message.
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#[derive(Debug,PartialEq,Eq)]
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enum DivisionError {
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@ -19,27 +20,6 @@ struct NotDivisibleError {
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// This function calculates a/b if a is divisible by b.
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// Otherwise it returns a suitable error.
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fn divide(a: i32, b: i32) -> Result<i32,DivisionError> {
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if b == 0 {
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}
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match a % b {
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}
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}
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// these print functions exist, so you have to satisfy their input types in the main function
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fn print_list_of_results(l: Vec<Result<i32,DivisionError>>) {
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println!("{:?}", l);
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}
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fn print_result_with_list(r: Result<Vec<i32>,DivisionError>) {
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// side quest: why is there no semicolon in this function?
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match r {
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Ok(v) => println!("All numbers were successfully divided: {:?}", v),
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Err(e) => match e {
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DivisionError::NotDivisible(nde) => println!("Failed to divide {} by {}: Not divisible!", nde.divident, nde.divisor),
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DivisionError::DivideByZero => println!("Can't divide by zero"),
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},
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};
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}
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#[allow(dead_code)]
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@ -54,9 +34,11 @@ fn main() {
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assert_eq!(divide(81,9),Ok(9));
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assert_eq!(divide(81,6),Err(DivisionError::NotDivisible(NotDivisibleError{divident:81,divisor:6})));
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assert_eq!(divide(81,0),Err(DivisionError::DivideByZero));
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assert_eq!(divide(0,81),Ok(0));
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println!("Your divide function seems to work! Good Job.");
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/* Second part of main. Uncomment to continue.
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// Don't change these numbers. It will break the assertions later in the code.
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let numbers = vec![27,297,38502,81];
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let division_results = // Do not convert the results into a Vec yet. Leave them iterable for now.
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@ -64,13 +46,16 @@ fn main() {
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match operation_mode {
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OperationMode::ResultWithList => {
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print_result_with_list(x);
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println!("{:?}", x);
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assert_eq!(format!("{:?}",x), "Ok([1, 11, 1426, 3])");
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},
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OperationMode::ListOfResults => {
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print_list_of_results(x);
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println!("{:?}", x);
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assert_eq!(format!("{:?}",x), "[Ok(1), Ok(11), Ok(1426), Ok(3)]");
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},
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} */
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}
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*/
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}
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@ -90,6 +75,20 @@ fn main() {
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@ -126,3 +125,40 @@ fn main() {
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// Major hint: Have a look at the Iter trait and at the explanation of its collect function. Especially the part about Result is interesting.
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// Final comments
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// When you call the function `print_result_with_list` with x, you don't need any type annotations on x anymore.
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// The compiler can infer its type through the function's input type.
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#[allow(dead_code)]
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// Don't use this function to solve the exercise
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fn print_result_with_list(r: Result<Vec<i32>,DivisionError>) {
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// side quest: why is there no semicolon in this function?
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match r {
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Ok(v) => println!("All numbers were successfully divided: {:?}", v),
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Err(e) => match e {
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DivisionError::NotDivisible(nde) => println!("Failed to divide {} by {}: Not divisible!", nde.divident, nde.divisor),
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DivisionError::DivideByZero => println!("Can't divide by zero"),
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},
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};
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}
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@ -23,10 +23,13 @@ fn divide(a: i32, b: i32) -> Result<i32,DivisionError> {
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}
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}
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// these print functions exist, so you have to satisfy their input types in the main function
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fn print_list_of_results(l: Vec<Result<i32,DivisionError>>) {
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println!("{:?}", l);
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#[allow(dead_code)]
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enum OperationMode {
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ListOfResults,
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ResultWithList,
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}
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#[allow(dead_code)]
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fn print_result_with_list(r: Result<Vec<i32>,DivisionError>) {
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// side quest: why is there no semicolon in this function?
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match r {
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@ -38,12 +41,6 @@ fn print_result_with_list(r: Result<Vec<i32>,DivisionError>) {
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};
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}
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#[allow(dead_code)]
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enum OperationMode {
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ListOfResults,
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ResultWithList,
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}
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fn main() {
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// These asserts check that your `divide` function works.
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// In production code these would be tests
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@ -51,6 +48,7 @@ fn main() {
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assert_eq!(divide(81,6),Err(DivisionError::NotDivisible(NotDivisibleError{divident:81,divisor:6})));
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assert_eq!(divide(81,0),Err(DivisionError::DivideByZero));
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println!("Your divide function seems to work! Good Job.");
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// Don't change these numbers. It will break the assertions later in the code.
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let numbers = vec![27,297,38502,81];
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let numbers_iterator = numbers.into_iter();
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let division_results = numbers_iterator.map(|n| divide(n, 27));
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@ -58,11 +56,13 @@ fn main() {
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match operation_mode {
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OperationMode::ResultWithList => {
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let x : Result<Vec<_>,_> = division_results.collect();
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print_result_with_list(x);
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//print_result_with_list(x);
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assert_eq!(format!("{:?}",x), "Ok([1, 11, 1426, 3])");
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},
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OperationMode::ListOfResults => {
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let x : Vec<_> = division_results.collect();
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print_list_of_results(x);
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println!("{:?}", x);
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assert_eq!(format!("{:?}",x), "[Ok(1), Ok(11), Ok(1426), Ok(3)]");
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},
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}
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}
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