where am I going wrong with this function?

Question

So i'm supposed to Move all palindrome numbers from mValues vector to mPalindromes vector

and the only hints I was given was a pseudo code: // iterate through the main values vector // if the value is a palindrome // add it to the palindrome vector // remove it from the values vector

and this is what I came up with:

for (int i = 0; i < mValues.size(); i++)
    {
        if (IsPalindromeNumber(mValues[i]) )
        {
            mPalindromes.push_back(mValues[i]);

            mValues.pop_back();

            
        }
    }

If anyone could tell me where I went wrong I would appreciate it.

edit: I figured it out the problem was I was using erase instead of popback.

@AndrewCheong yes i was given the function IsPalindromeNumber, it checks if the number is a Palindrome — Neteroh, Jul 10 '20 at 02:22
@Jorengarenar ok so i just made that correction it did not work — Neteroh, Jul 10 '20 at 02:26
@Jorengarenar did it im new to stack so idk how to do some stuff yet — Neteroh, Jul 10 '20 at 02:35
You need to provide [Minimal, Reproducible Example](https://stackoverflow.com/help/minimal-reproducible-example) — Jorengarenar, Jul 10 '20 at 02:48

Jeffrey · Answer 1 · 2020-07-10T02:51:42.853

2

When you do

mValues.erase(mValues.begin() + i); // with correction from comments

you modify mValues, so i starts indexing elsewhere in mValues. One fix would be

mValues.erase(mValues.begin() + i);
i--;

but it's not very elegant. It would be better to copy the palindromes to mPalindromes and then use std::remove_if or something, in a second pass.

edited Jul 10 '20 at 02:51

answered Jul 10 '20 at 02:28

Jeffrey

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Hmm... If only there were some [combination of `copy` and `remove_if`](https://en.cppreference.com/w/cpp/algorithm/remove_copy) :) – chris Jul 10 '20 at 02:39

where am I going wrong with this function?

1 Answers1