{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Errors"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "1."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "vscode": {
     "languageId": "rust"
    }
   },
   "outputs": [],
   "source": [
    "// FILL in the blanks and FIX the errors\n",
    "use std::num::ParseIntError;\n",
    "use std::num::IntErrorKind::InvalidDigit\n",
    "\n",
    "fn multiply(n1_str: &str, n2_str: &str) -> Result<i32, ParseIntError> {\n",
    "    let n1 = n1_str.parse::<i32>();\n",
    "    let n2 = n2_str.parse::<i32>();\n",
    " \n",
    "    n1 * n2\n",
    "}\n",
    "\n",
    "fn main() {\n",
    "    let result = multiply(\"10\", \"2\");\n",
    "    assert_eq!(result, Ok(20));\n",
    "\n",
    "    let result = multiply(\"t\", \"2\");\n",
    "    assert_eq!(result.err().unwrap().kind(), &InvalidDigit);\n",
    "\n",
    "    println!(\"Success!\");\n",
    "}\n",
    "\n",
    "main();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "2."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "vscode": {
     "languageId": "rust"
    }
   },
   "outputs": [],
   "source": [
    "use std::fs;\n",
    "use std::io;\n",
    "use std::num;\n",
    "\n",
    "enum CliError {\n",
    "    IoError(io::Error),\n",
    "    ParseError(num::ParseIntError),\n",
    "}\n",
    "\n",
    "impl From<io::Error> for CliError {\n",
    "    // TODO: implement the trait\n",
    "}\n",
    " \n",
    "impl From<num::ParseIntError> for CliError {\n",
    "    // TODO: implement the trait\n",
    "}\n",
    "\n",
    "fn open_and_parse_file(file_name: &str) -> Result<i32, CliError> {\n",
    "    // ? automatically converts io::Error to CliError\n",
    "    let contents = fs::read_to_string(&file_name)?;\n",
    "    // num::ParseIntError -> CliError\n",
    "    let num: i32 = contents.trim().parse()?;\n",
    "    Ok(num)\n",
    "}\n",
    "\n",
    "fn main() {\n",
    "    println!(\"Success!\");\n",
    "}\n",
    "\n",
    "main();"
   ]
  }
 ],
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   "display_name": "Rust",
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   "name": "rust"
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   "codemirror_mode": "rust",
   "file_extension": ".rs",
   "mimetype": "text/rust",
   "name": "Rust",
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