Removed " character from allowed_chars, allow second optional argument for disallowed characters, error handling for missing or incorrect arguments

src/main.rs

@@ -1,21 +1,50 @@
 use std::env;
 
 fn main() {
-    // Take in two command line arguments, one i32 and one str
+    // Take in two command line arguments, one i32 and one optional String
     let args: Vec<String> = env::args().collect();
-    let new_password_length: i32 = args[1].parse().unwrap();
-    let allowed_chars: &str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890-=`~!@#$%^&*()_+[]\\{}|;':\",./<>?";
-
-    // Generate a random string of length n
-    let mut new_password = String::new();
-    for _ in 0..new_password_length {
-        new_password.push(
-            allowed_chars.chars()
-                .nth(rand::random::<usize>() % allowed_chars.len())
-                .unwrap()
-        );
+    if args.len() < 2 { // Make sure at least one argument is provided
+        println!("Error: First argument must be a valid integer (Ex. 32)");
+        println!("Argument not supplied");
+        return;
     }
 
-    // Print the new password
-    println!("{}", new_password);
+    let new_password_length: Option<i32> = args[1].parse().ok();
+    if new_password_length.is_none() { // Make sure i32 parsed correctly
+        println!("Error: First argument must be a valid integer (Ex. 32)");
+        return;
+    }
+
+    // Disallowed_chars is an optional argument
+    let disallowed_chars: Option<&String> = args.get(2);
+
+    let mut allowed_chars: String = String::from("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890-=`~!@#$%^&*()_+[]\\{}|;':,./<>?");
+
+    // Remove disallowed characters from allowed_characters if disallowed_chars is specified
+    if let Some(disallowed_chars) = disallowed_chars {
+        for disallowed_char in disallowed_chars.chars() {
+            allowed_chars = allowed_chars.replace(disallowed_char, "");
+        }
+
+        if allowed_chars.len() == 0 { // Make sure there are still characters left to use
+            println!("Error: You have disallowed all characters");
+            println!("The allowed character set includes: abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890-=`~!@#$%^&*()_+[]\\{{}}|;':,./<>?");
+            return;
+        }
+    }
+
+    if let Some(new_password_length) = new_password_length { // Unwrap Option in i32
+        // Generate a random string of length n
+        let mut new_password = String::new();
+        for _ in 0..new_password_length {
+            new_password.push(
+                allowed_chars.chars()
+                    .nth(rand::random::<usize>() % allowed_chars.len())
+                    .unwrap()
+            );
+        }
+
+        // Print the new password
+        println!("{}", new_password);
+    }
 }