完成第13章节

exercises/13_error_handling/errors1.rs

@@ -9,14 +9,12 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-use std::error::Error;
+
 use std::result::Result;
 
 
 
-
-pub fn generate_nametag_text(name: String) -> Result<String, Box<dyn Error>> {
+pub fn generate_nametag_text(name: String) -> Result<String,String> {
     if name.is_empty() {
         // Empty names aren't allowed.
         Err("`name` was empty; it must be nonempty.".into())

exercises/13_error_handling/errors2.rs

@@ -19,14 +19,16 @@
 // 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<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
+    let qty = match item_quantity.parse::<i32>() {
+        Ok(qty) => {qty},
+        Err(r) => { return Err(r)},
+    };
 
     Ok(qty * cost_per_item + processing_fee)
 }

exercises/13_error_handling/errors3.rs

@@ -7,11 +7,10 @@
 // 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";
 
@@ -23,6 +22,7 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+    Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {

exercises/13_error_handling/errors4.rs

@@ -3,7 +3,7 @@
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+
 
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
@@ -17,7 +17,13 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm... Why is this always returning an Ok value?
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value <0{
+            Err(CreationError::Negative)
+        }else if value ==0{
+            Err(CreationError::Zero)
+        }else{
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
     }
 }
 

exercises/13_error_handling/errors5.rs

@@ -22,14 +22,15 @@
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+
 
 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<dyn ???>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);

exercises/13_error_handling/errors6.rs

@@ -9,7 +9,7 @@
 // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+
 
 use std::num::ParseIntError;
 
@@ -26,12 +26,15 @@ impl ParsePosNonzeroError {
     }
     // 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<PositiveNonzeroInteger, ParsePosNonzeroError> {
     // TODO: change this to return an appropriate error instead of panicking
     // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
+    let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parseint)?;
     PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
 }