day 1: parse input

day_01/src/main.rs

@@ -1,3 +1,42 @@
-fn main() {
-    println!("Hello, world!");
+use std::error::Error;
+use std::fs::File;
+use std::io::{self, BufReader, prelude::*};
+use std::{env, fs};
+
+fn parse_line(line: &str) -> Result<(i64, i64), Box<dyn Error>> {
+    // Split line on whitespace
+    // Expecting "88789   64926"
+    // Should end up with two string, if not something is wrong.
+    let split_line: Vec<_> = line
+        .splitn(2, char::is_whitespace)
+        .map(|elm| elm.trim())
+        .collect();
+
+    // Parse and return our two elements
+    let first_element = split_line[0].parse::<i64>()?;
+    let second_element = split_line[1].parse::<i64>()?;
+    return Ok((first_element, second_element));
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    // Handle command input
+    let args: Vec<String> = env::args().collect();
+    if args.len() != 2 {
+        panic!(
+            "{} must be run with a single argument of files name!",
+            &args[0]
+        )
+    }
+    let input_file_string = &args[1];
+
+    let input_file = File::open(input_file_string)?;
+    let input_reader = BufReader::new(input_file);
+
+    for (index, line) in input_reader.lines().enumerate() {
+        let line = line?;
+        let parsed_line = parse_line(&line)?;
+        println!("({},{})", parsed_line.0, parsed_line.1);
+    }
+
+    return Ok(());
 }