first

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
-		 
-		 return 'a';
-	 }
-	 
-	 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
-		 
-		 return "Encryptred message";
-	 }
-	
+// 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 ascii = (int)theChar;//character turned into ascii value to shift by theOffset easily
+  
+  char character = 'a';//declaring the return variable
+  
+  if((ascii>64 && ascii<92) || (96< ascii &&  ascii < 123))//if the ascii value is withing the letter ranges then it is shifted
+  {
+   
+   character = (char) (ascii+theOffset); //applies the shift and turns the ascii value back into a char
+   
+   if((ascii+theOffset) > 122)
+   {
+    character = (char)((ascii+theOffset)-26); //if the letter is shifted past z it loops back around to a
+   }
+   
+   else if((ascii+theOffset) >90 && (ascii+theOffset)<97)
+   {
+    character = (char)((ascii+theOffset)+26); //if the character is shifted below a then it loops around to z
+   }
+   
+   else if((ascii+theOffset) <65)
+   {
+    character = (char)((ascii+theOffset)+26);//if the character is shifted below upper case A then it loops around to Z
+   }
+   
+   else if((ascii+theOffset) <97 && (ascii+theOffset)>90)
+   {
+    character = (char)((ascii+theOffset)-26);//if the character is shifted past upper case Z then it loops around to A
+   }
+  }
+  else
+  {
+   character = (char)ascii;// if the character is not a letter it remains the same;
+  }
+  return character;//returns character after shift
+ }
+ 
+ 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
+  char[] message = theMessage.toCharArray();//creates a char array
+  for(int i =0;i<theMessage.length();i++)
+  {
+   message[i] = enryptedCharacter(message[i],theOffset);//steps through the array and shifts the characters by theOffset
+  }
+  String encryptedMessage = "";//declaring return string
+  for(int j=0;j<message.length;j++)
+  {
+   encryptedMessage = encryptedMessage + message[j];//steps through the char array a final time and concatenates the elements into a string
+  }
+  return encryptedMessage;
+ }
+
 }