ch9 done

ch9/recoverable-errors/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "recoverable-errors"
+version = "0.1.0"

ch9/recoverable-errors/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "recoverable-errors"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

ch9/recoverable-errors/src/main.rs

@@ -0,0 +1,101 @@
+// Uses the Result enum
+
+use std::error::Error;
+use std::fs::{self, File};
+use std::io::{self, ErrorKind, Read};
+
+// Can actually return a result.
+// Need final line to be Ok(())
+fn main() -> Result<(), Box<dyn Error>> {
+    let greeting_file_result = File::open("hello.txt");
+
+    // let greeting_file = match greeting_file_result {
+    //     Ok(file) => file,
+    //     Err(error) => panic!("Problem opening file: {error:?}"),
+    // };
+
+    // Matching on different errors
+    // let greeting_file = match greeting_file_result {
+    //     Ok(file) => file,
+    //     Err(error) => match error.kind() {
+    //         std::io::ErrorKind::NotFound => match File::create("hello.txt") {
+    //             Ok(fc) => fc,
+    //             Err(e) => panic!("Problem creating file: {e:?}"),
+    //         },
+    //         other_error => {
+    //             panic!("Problem opening file: {other_error:?}");
+    //         }
+    //     },
+    // };
+
+    // Using closures this time
+    // let greeting_file = File::open("hello.txt").unwrap_or_else(|error| {
+    //     if error.kind() == ErrorKind::NotFound {
+    //         File::create("hello.txt").unwrap_or_else(|error| {
+    //             panic!("Problem creating file: {error:?}");
+    //         })
+    //     } else {
+    //         panic!("Problem opening file: {error:?}");
+    //     }
+    // });
+
+    // shortcuts for panic on error
+    // let greeting_file = File::open("hello.txt").unwrap();
+
+    let greeting_file =
+        File::open("hello.txt").expect("hello.txt should be included in this project");
+
+    // propagating errors
+    // instead of handling error within function itself, return
+    // error to the calling code so it can decide what to do
+    read_username_from_file();
+
+    // A shortcut for propapating errors: the ? Operator
+    read_username_from_file_question();
+
+    // The code below errors
+    // The ? can only be used in a function that returns Option or Result.
+    // Similar to raising into a Monad in haskell with the pure function in a do statement.
+    // let greeting_file = File::open("hello.txt")?;
+
+    println!("Should be Some('a'): {:?}", last_char_of_first_line("line"));
+    println!("Should be None: {:?}", last_char_of_first_line(""));
+
+    Ok(())
+}
+
+fn read_username_from_file() -> Result<String, io::Error> {
+    let username_file_result = File::open("hello.txt");
+
+    let mut username_file = match username_file_result {
+        Ok(file) => file,
+        Err(e) => return Err(e),
+    };
+
+    let mut username = String::new();
+
+    match username_file.read_to_string(&mut username) {
+        Ok(_) => Ok(username),
+        Err(e) => Err(e),
+    }
+}
+
+fn read_username_from_file_question() -> Result<String, io::Error> {
+    // let mut username_file = File::open("hello.txt")?;
+    // let mut username = String::new();
+    // username_file.read_to_string(&mut username)?;
+    // Ok(username)
+
+    // Can chain function calls
+    // let mut username = String::new();
+    // File::open("hello.txt")?.read_to_string(&mut username)?;
+    // Ok(username)
+
+    // Even faster way to write this
+    // Just reads a file into a string
+    fs::read_to_string("hello.txt")
+}
+
+fn last_char_of_first_line(text: &str) -> Option<char> {
+    text.lines().next()?.chars().last()
+}

ch9/to-panic-or-not-to-panic/Cargo.lock

@@ -0,0 +1,158 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "bitflags"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c8214115b7bf84099f1309324e63141d4c5d7cc26862f97a0a857dbefe165bd"
+
+[[package]]
+name = "cfg-if"
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+
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+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+ "wasi",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.171"
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+ "zerocopy",
+]
+
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+ "rand_chacha",
+ "rand_core",
+ "zerocopy",
+]
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+ "ppv-lite86",
+ "rand_core",
+]
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+ "getrandom",
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+
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "to-panic-or-not-to-panic"
+version = "0.1.0"
+dependencies = [
+ "rand",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
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+dependencies = [
+ "wit-bindgen-rt",
+]
+
+[[package]]
+name = "wit-bindgen-rt"
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+ "bitflags",
+]
+
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+ "zerocopy-derive",
+]
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]

ch9/to-panic-or-not-to-panic/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "to-panic-or-not-to-panic"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rand = "0.9.0"

ch9/to-panic-or-not-to-panic/src/main.rs

@@ -0,0 +1,45 @@
+use rand::Rng;
+use std::cmp::Ordering;
+use std::io;
+use std::net::IpAddr;
+
+fn main() {
+    let home: IpAddr = "127.0.0.1"
+        .parse()
+        .expect("Hardcoded IP address should be valid");
+
+    // creating custom types for validation
+
+    println!("Guess the number!");
+
+    let secret_number = rand::thread_rng().gen_range(1..=100);
+
+    loop {
+        println!("Please input your guess.");
+
+        let mut guess = String::new();
+
+        io::stdin()
+            .read_line(&mut guess)
+            .expect("Failed to read line");
+
+        let guess: i32 = match guess.trim().parse() {
+            Ok(num) => num,
+            Err(_) => continue,
+        };
+
+        if guess < 1 || guess > 100 {
+            println!("The secret number will be between 1 and 100.");
+            continue;
+        }
+
+        match guess.cmp(&secret_number) {
+            Ordering::Less => println!("Too small!"),
+            Ordering::Greater => println!("Too big!"),
+            Ordering::Equal => {
+                println!("You win!");
+                break;
+            }
+        }
+    }
+}

ch9/unrecoverable-errors/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "unrecoverable-errors"
+version = "0.1.0"

ch9/unrecoverable-errors/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "unrecoverable-errors"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

ch9/unrecoverable-errors/src/main.rs

@@ -0,0 +1,15 @@
+// Rust will try to clean up the program after a panic! is reached
+// If want a smaller binary size, set:
+// ```cargo.toml
+// [profile.release]
+// panic = 'abort'
+// ```
+// to let the operating system handle the clean up.
+// When Rust handles this, named unwinding
+//
+// Use RUST_BACKTRACE=1 %command% to see the full backtrace
+//   in case the panic isn't from your code directly.
+
+fn main() {
+    panic!("crash and burn");
+}