diff --git a/' b/'
deleted file mode 100644
index ddef96d..0000000
--- a/'
+++ /dev/null
@@ -1,39 +0,0 @@
-use std::env;
-use std::fs;
-use std::process;
-
-fn main() {
-    let args: Vec<String> = env::args().collect();
-
-    let config = Config::build(&args).unwrap_or_else(|err| {
-        println!("Problem parsing arguments: {err}");
-        process::exit(1);
-    });
-
-    run(config);
-}
-
-fn run(config: Config) -> Result<(), Box<dyn Error>> {
-    let contents =
-        fs::read_to_string(config.file_path).expect("Should have have been able to read the file!");
-
-    println!("With text:\n{contents}");
-}
-
-struct Config {
-    query: String,
-    file_path: String,
-}
-
-impl Config {
-    fn build(args: &[String]) -> Result<Config, &'static str> {
-        if args.len() < 3 {
-            return Err("not enough arguments!");
-        }
-
-        let query = args[1].clone();
-        let file_path = args[2].clone();
-
-        Ok(Config { query, file_path })
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index 5fde8ee..670ddb8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,10 +1,18 @@
 use std::error::Error;
-use std::fs;
+use std::{env, fs};
 
 pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
     let contents = fs::read_to_string(config.file_path)?;
 
-    println!("With text:\n{contents}");
+    let results = if config.ignore_case {
+        search_case_insensitive(&config.query, &contents)
+    } else {
+        search(&config.query, &contents)
+    };
+
+    for line in results {
+        println!("{line}");
+    }
 
     Ok(())
 }
@@ -12,6 +20,7 @@ pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
 pub struct Config {
     pub query: String,
     pub file_path: String,
+    pub ignore_case: bool,
 }
 
 impl Config {
@@ -23,6 +32,68 @@ impl Config {
         let query = args[1].clone();
         let file_path = args[2].clone();
 
-        Ok(Config { query, file_path })
+        let ignore_case = env::var("IGNORE_CASE").is_ok();
+
+        Ok(Config {
+            query,
+            file_path,
+            ignore_case,
+        })
+    }
+}
+
+fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+    let mut results = Vec::new();
+
+    for line in contents.lines() {
+        if line.contains(query) {
+            results.push(line);
+        }
+    }
+
+    results
+}
+
+fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+    let mut results = Vec::new();
+    let query = query.to_lowercase();
+
+    for line in contents.lines() {
+        if line.to_lowercase().contains(&query) {
+            results.push(line);
+        }
+    }
+
+    results
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn case_sensitive() {
+        let query = "duct";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.";
+
+        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
+    }
+
+    #[test]
+    fn case_insensitive() {
+        let query = "rUsT";
+        let contents = "\
+Rust:
+safe, fast, productive.
+Pick three.
+Trust me.";
+
+        assert_eq!(
+            vec!["Rust:", "Trust me."],
+            search_case_insensitive(query, contents)
+        );
     }
 }
diff --git a/src/main.rs b/src/main.rs
index 881abb4..5224b85 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,15 +7,12 @@ fn main() {
     let args: Vec<String> = env::args().collect();
 
     let config = Config::build(&args).unwrap_or_else(|err| {
-        println!("Problem parsing arguments: {err}");
+        mprintln!("Problem parsing arguments: {err}");
         process::exit(1);
     });
 
-    println!("Searching for {}", config.query);
-    println!("In file {}", config.file_path);
-
     if let Err(e) = minigrep::run(config) {
-        println!("Application error: {e}");
+        eprintln!("Application error: {e}");
         process::exit(1);
     }
 }