Tell us what’s happening:
In for loop, I set the condition ‘i’ to be less than or equal to the length of the string, but ‘i’ never reaches the length. Hence, code does not pass the last condition of the test.
Why ‘i’ won’t reach 3 in this example?
Many thanks in advance.
Your code so far
function fearNotLetter(str) {
for(let i=0;i<=str.length;i++){
if(str.charCodeAt(i+1) - str.charCodeAt(i) !==1 ){
return String.fromCharCode(str.charCodeAt(i)+1)
}
/*i never reaches the length of the string, even though condition is set
to i <= str.length */
// console.log('i='+i)
//console.log(String.fromCharCode(str.charCodeAt(i)))
// console.log('array length='+str.length)
}
}
fearNotLetter("abc");
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// Function
function fearNotLetter(str) {
// Loop over all string entries
for (let i = 0; i <= str.length; i++) {
// Debugging output
console.log("i = " + i);
console.log(" - curr char: " + str[i]);
console.log(" - next char: " + str[i + 1]);
// Return if gap is found
if (str.charCodeAt(i + 1) - str.charCodeAt(i) !== 1) {
return String.fromCharCode(str.charCodeAt(i) + 1)
}
}
}
// Test
console.log("Return: " + fearNotLetter("abcdefghijklmnopqrstuvwxyz"));
This outputs:
Click Here for Long Output Log
i = 0
- curr char: a
- next char: b
i = 1
- curr char: b
- next char: c
i = 2
- curr char: c
- next char: d
i = 3
- curr char: d
- next char: e
i = 4
- curr char: e
- next char: f
i = 5
- curr char: f
- next char: g
i = 6
- curr char: g
- next char: h
i = 7
- curr char: h
- next char: i
i = 8
- curr char: i
- next char: j
i = 9
- curr char: j
- next char: k
i = 10
- curr char: k
- next char: l
i = 11
- curr char: l
- next char: m
i = 12
- curr char: m
- next char: n
i = 13
- curr char: n
- next char: o
i = 14
- curr char: o
- next char: p
i = 15
- curr char: p
- next char: q
i = 16
- curr char: q
- next char: r
i = 17
- curr char: r
- next char: s
i = 18
- curr char: s
- next char: t
i = 19
- curr char: t
- next char: u
i = 20
- curr char: u
- next char: v
i = 21
- curr char: v
- next char: w
i = 22
- curr char: w
- next char: x
i = 23
- curr char: x
- next char: y
i = 24
- curr char: y
- next char: z
i = 25
- curr char: z
- next char: undefined
Return: {
It looks like you have some funny business at the end of your loop. You are overstepping by two iterations. Do you see how?
Thanks for the quick reply. For the avatar comment as well (big Star Trek fan )
Hmmm…not sure I follow your feedback though. In this debugging scenario, string is 26 characters long. My loop reaches 25, whilst it should reach 26. Don’t know why. It should be simple: string is 26 characters long => exit when ‘i’ equals 26. That for some reason does not happen.
Hmmmm…
says “The current index is i = 25 and the current character is z. When I look ahead to character i = 26, that character is undefined. Therefore, I will return the character corresponding to the character code for the character at index i + 1”.
Unpacking the output like this highlights the issue. The character z is an index 25. There is no other character to compare z with because z is at the end of the string. Everything the loop tries to do after it tries to look at a character that doesn’t exist isn’t going to work.
Right. And you will return undefined if you change your loop bound.
You are comparing the first character to the second, the second to the third, and so on. This means you should compare the second to last character to the last character and stop. Right now you are comparing character 25 to character 26 (which doesn’t exist) and character 26 to character 27 (which also does not exist).
I was able to get your code to pass by only changing your loop bound.
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