Completing the Lab

Part 2: Checking for a Palindrome

In order to check if str is a palindrome, you must check if the first character is the same as the last character, then check if the second character is the same as the second to last character, then check if the third character is the same as the third to last character, and so forth.

As a reminder, you can get a single character from a string by using either array brackets ([ ]) or the charAt method of a String. This means that both of these will get the character at index 3:

var c1 = str.charAt(3);
var c2 = str[3];

Therefore, to check for a palindrome, you must:

1. Create a for-loop to go through each character in the string.
2. For each i^th character, check if the i^th character is the same as the i^th character from the end; if it is not, it is not a palindrome and you should return false immediately.
3. If all of your checks in your for-loop were successful, you have never returned false. Therefore, the string must be a palindrome and you should return true.

Step 2 in the previous list can be challenging. This table may help you understand how you need to complete Step 2:

Example value of str	i	ith character	ith character from the end	Equal?
"racecar"	0	[i] == [0] == "r"	[str.length - 1 - i] == [7 - 1 - 0] == [6] == "r"	Yes
	1	[i] == [1] == "a"	[str.length - 1 - i] == [7 - 1 - 1] == [5] == "a"	Yes
	2	[i] == [2] == "c"	[str.length - 1 - i] == [7 - 1 - 2] == [5] == "c"	Yes
	3	[i] == [3] == "e"	[str.length - 1 - i] == [7 - 1 - 3] == [4] == "e"	Yes
	4	[i] == [4] == "c"	[str.length - 1 - i] == [7 - 1 - 4] == [2] == "c"	Yes
	5	[i] == [5] == "a"	[str.length - 1 - i] == [7 - 1 - 5] == [1] == "a"	Yes
	6	[i] == [6] == "r"	[str.length - 1 - i] == [7 - 1 - 6] == [0] == "r"	Yes
	All equal, therefore return true
"cs105"	0	[i] == [0] == "c"	[str.length - 1 - i] == [5 - 1 - 0] == [4] == "5"	No
	"c" != "5", therefore return false immediately

Submission

To submit your lab, you must submit your lab6.js to the CS 105 website. You should submit ONLY .js file. You do not need to submit the other files in the folder. Click here to submit the lab!