part three

assessment03-18/src/AssessmentPartThree.java

+
+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
+	// letter that that number of places away from it.
+	// So if an offset value of 1 is chosen, each letter is replaced by the one after it
+	// - so a becomes b, b becomes c, etc
+	// If a value of -2 is chosen a becomes y, b becomes z and so on
+	
+	 public char enryptedCharacter(char theChar, int theOffSet)
+	 {
+		 // 05 - encryptedCharacter
+		 // Complete this method so that it returns the encrypted character for
+		 // theChar when and offset of theOffset is used
+		 // So if theChar='m' and theOffset is 3 the method will return 'p'
+		 // Lower case characters remain lower case, upper case remain upper case
+		 // Any other characters are returned unchanged
+		 
+		 
+		 int charNum = (int) theChar;
+		 
+		 if((65  <= charNum && charNum <= 90)) 
+		 {
+			 
+			 if(theOffSet >0) {
+			 for(int i = theOffSet; i !=0; i--) 
+			 {
+				 charNum = charNum +1;
+				 if(charNum >90) 
+				 {
+					 charNum = 65;
+				 }
+			 }
+			 theChar = (char)charNum;
+			 return theChar;
+			 }
+			 else 
+			 {
+				 for(int i = theOffSet; i !=0; i++) 
+				 {
+					 charNum = charNum -1;
+					 if(charNum < 65) 
+					 {
+						 charNum = 90;
+					 }
+					 
+				 }
+				 theChar = (char)charNum;
+				 return theChar;
+			 }
+		 }
+		 else if(97  <= charNum && charNum <= 122) 
+		 {
+			 if(theOffSet >0) {
+			 for(int i = theOffSet; i !=0; i--) 
+			 {
+				 charNum = charNum +1;
+				 if(charNum >122) 
+				 {
+					 charNum = 97;
+				 }
+				 
+			 }
+			 theChar = (char)charNum;
+			 return theChar;
+			 }
+			 else 
+			 {
+				 for(int i = theOffSet; i !=0; i++) 
+				 {
+					 charNum = charNum -1;
+					 if(charNum < 97) 
+					 {
+						 charNum = 122;
+					 }
+					 
+				 }
+				 theChar = (char)charNum;
+				 return theChar;
+			 }
+		 }
+		 else 
+		 {
+			 return theChar;
+		 }
+	 }
+	 
+	 public String encryptedString(String theMessage, int theOffSet)
+	 {
+		 // 06 - encryptedMessage
+		 // Complete this method so that it uses encryptedCharacter to 
+		 // return the encrypted version of theMessage using theOffset
+		 String encryptedMessage = ""; 
+		 for(int i = 0; i < theMessage.length(); i++) 
+		 {
+			 encryptedMessage += enryptedCharacter(theMessage.charAt(i), theOffSet);
+		 }
+		 return encryptedMessage;
+	 }
+	
+}