Commit

crypto/caeser_cipher/src/main.rs

@@ -0,0 +1,49 @@
+fn main() {
+    println!("Hello, world!");
+}
+
+fn caesar(plain: &str, rshift: u8) -> String {
+    let alphabet = "abcdefghijklmnopqrstuvwxyz";
+    let mut out = String::new();
+    for c in plain.chars() {
+        if !c.is_alphabetic() {
+            out.push(c);
+            continue;
+        }
+        let num = (alphabet
+            .bytes()
+            .position(|a| a == c.to_lowercase().next().unwrap() as u8)
+            .unwrap() as u8
+            + rshift)
+            % 26;
+        let a = alphabet.chars().nth(num as usize).unwrap();
+        let a = if c.is_uppercase() {
+            a.to_uppercase().next().unwrap()
+        } else {
+            a
+        };
+        out.push(a);
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rot13() {
+        let message = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+        let shift = 13;
+        let out = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm";
+        assert_eq!(caesar(message, shift), out);
+    }
+
+    #[test]
+    fn wiki_caesar() {
+        let message = "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG";
+        let shift = 23;
+        let out = "QEB NRFZH YOLTK CLU GRJMP LSBO QEB IXWV ALD";
+        assert_eq!(caesar(message, shift), out);
+    }
+}