mod word_utils;
use std::collections::HashMap;
+use std::io::{prelude::*, ErrorKind};
+use std::fs::File;
use word_utils::{first_word, second_word};
-fn main() {
- // strings and functions
+fn test_strings() {
let s = String::from("Hello world");
println!("first word: '{}'", first_word(&s));
println!("second word: '{}'", second_word(&s).unwrap());
Some(w) => println!("match: second word of '{}' exists: {}", s2, w),
None => println!("match: second word of '{}' does not exist", s2),
}
+}
- // vectors
+fn test_vectors() {
let v1 = vec![1, 2, 3];
println!("statically initialized vector: {:?}", v1);
for el in &v2 {
println!("{}", el);
}
+}
- // hash maps
+fn test_hashmaps() {
let mut scores = HashMap::new();
scores.insert("john", 10);
scores.insert("mary", 20);
.collect();
println!("collect_scores after rebuilding with doubling: {:?}", collect_scores);
}
+
+fn read_file(path: &str) -> Result<String, std::io::Error> {
+ let mut s = String::new();
+ File::open(path)?
+ .read_to_string(&mut s)?;
+ Ok(s)
+}
+
+fn test_files() {
+ if let Ok(mut f) = File::open("Cargo.toml") {
+ let mut contents = String::new();
+ match f.read_to_string(&mut contents) {
+ Ok(len) => println!("successfully opened Cargo.toml: {:?}, contents {} bytes:\n{}\n----------", f, len, contents),
+ Err(e) => panic!("could not read file: {:?}", e)
+ }
+ } else {
+ println!("could not open Cargo.toml");
+ }
+
+ // alternative form, more specific error checking
+ let mut f = File::open("Cargo.toml").unwrap_or_else(|e| {
+ if e.kind() == ErrorKind::NotFound {
+ println!("Cargo.toml not found, falling back to /dev/null");
+ // need to return a File
+ File::open("/dev/null").unwrap()
+ } else {
+ panic!("Could not open Cargo.toml: {:?}", e);
+ }
+ });
+ let mut contents = String::new();
+ let len = f.read_to_string(&mut contents).unwrap_or_else(|e| {
+ panic!("Could not read file: {:?}", e);
+ });
+ println!("successfully opened Cargo.toml with unwrap_or_else: {:?}, contents {} bytes:\n{}\n----------", f, len, contents);
+
+ // using the '?' operator
+ match read_file("Cargo.toml") {
+ Ok(s) => println!("Cargo.toml contents:\n{}\n-------------", s),
+ Err(e) => println!("Could not open Cargo.toml: {:?}", e)
+ }
+}
+
+fn main() {
+ test_strings();
+ test_vectors();
+ test_hashmaps();
+ test_files();
+}