Print usage if no args or passwords given.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 9e18a85..b742d95 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -110,11 +110,20 @@ fn check(pw: Password) -> Result<(), Box<::std::error::Error>> {
     Ok(())
 }
 
+fn print_usage() {
+    println!("Usage: checkpw <pw>...");
+}
+
 fn main() {
-    let (_args, passwords) : (Vec<String>, Vec<String>) = env::args()
+    let (args, passwords) : (Vec<String>, Vec<String>) = env::args()
         .skip(1)
         .partition(|arg| arg.starts_with('-'));
 
+    if args.is_empty() && passwords.is_empty() {
+        print_usage();
+        return;
+    }
+
     for pw in passwords {
         check(Password::new(&pw)).unwrap();
     }