12:19 10/12/18

src/AssessmentPartThree.java

 
-public class AssessmentPartThree {
+public class AssessmentPartThree 
+{
 
 	// The simplest form of encryption is the rotation cipher (also known as Caeser's Cipher)
 	// An offset value is chosen to encrypt a message. Each letter is replaced by the
@@ -17,25 +18,31 @@ public class AssessmentPartThree {
 	// Lower case characters remain lower case, upper case remain upper case
 	// Any other characters are returned unchanged
 	  
-	//Uppercase characters
-	if((theChar >= 65) && (theChar <= 90)) //65 to 90 = A to B
-	{
-	theChar = (char) (((theChar - 65 + theOffset) % 26) + 65);
-	}
-	//Lowercase characters
-	else if((theChar >= 97) && (theChar <= 122)) // 97 to 122 = a to b
-	{
-	theChar = (char) (((theChar - 97 + theOffset) % 26) + 97);
-	}
-	/*
-	theChar = (char) (((theChar - 97 + theOffset) % 26) + 97); formulae
-	                      (theChar - 97 - ASCII a/A to give value between 1 and 26  
-	            + theOffset) + the offset value
-	                      (                           % 26) % modulo ensures value is always between 1 and 26
-	                    (                                  + 97) + ASCII a/A to return result to ASCII char
-	              (char) result needs to be casted to char 
-	*/
-	return theChar;
+		//Dealing with negative offsets
+		theOffset = (theOffset < 0) ? 26 + theOffset : theOffset;
+		//ensures that the offset will "wrap around"
+		
+		//Uppercase characters
+		if((theChar >= 65) && (theChar <= 90)) //65 to 90 = A to B
+		{
+			theChar = (char) (((theChar - 65 + theOffset) % 26) + 65);
+		}
+		//Lowercase characters
+		else if((theChar >= 97) && (theChar <= 122)) // 97 to 122 = a to b
+		{
+			theChar = (char) (((theChar - 97 + theOffset) % 26) + 97);
+		}
+		/*
+			theChar = (char) (((theChar - 97 + theOffset) % 26) + 97);		formulae
+		                       (theChar - 97 								- ASCII a/A to give value between 1 and 26  
+								             + theOffset)					+ the offset value
+		                      (                           % 26)				% modulo ensures value is always between 1 and 26
+		                     (                                  + 97)		+ ASCII a/A to return result to ASCII char
+		              (char) 												result needs to be casted to char 
+		*/
+		
+		return theChar;
+		//any non alphabetical chars will fall through and return original char
 	}
 
 	 
@@ -45,15 +52,15 @@ public class AssessmentPartThree {
 	// Complete this method so that it uses encryptedCharacter to 
 	// return the encrypted version of theMessage using theOffset
 	 
-	char chaMessageArr[] = theMessage.toCharArray();
-	char[] chaResultArr = new char[chaMessageArr.length];
+		char chaMessageArr[] = theMessage.toCharArray();
+		char[] chaResultArr = new char[chaMessageArr.length];
 	//initialising Arrays
 	  
 	for(int i = 0; i < chaMessageArr.length; i++)
 	//loop to run through each character in encrypted message
 	{
-	chaResultArr[i] = enryptedCharacter(chaMessageArr[i], theOffset);
-	//passing each character to decryption method and saving result in array
+		 chaResultArr[i] = enryptedCharacter(chaMessageArr[i], theOffset);
+		 //passing each character to decryption method and saving result in array
 	}
 	 
 	return (new String(chaResultArr));

src/AssessmentPartThreeTest.java

@@ -23,7 +23,10 @@ class AssessmentPartThreeTest {
 					"q,-3,n",
 					"G,6,M",
 					"5,-3,5",
-					"T,-7,M"
+					"T,-7,M",
+					"a,31,f",
+					"T,-33,M",
+					"!, 2, !"
 	})	
 	void testEnryptedCharacter(char theChar, int theOffset, char encChar) {
 		assertEquals(encChar,test.enryptedCharacter(theChar, theOffset));