How to use vector.erase() with an integer

Question

0.00/5 (No votes)

See more:

This is the code:

C++

for (int i = start; i < end; i++) {
  int pos = i;
  std::vector<char>::iterator it = (newArr.begin() + pos);
  newArr.erase(it);

newArr is a char vector. This crashes the program. I also tried doing just newArr.erase(newArr.begin()+pos) but same result.

What I have tried:

I tried changing the iterator code to just newArr.erase(newArr.begin()+pos) and it did not work any better.

Posted 3-Dec-21 8:48am

Member 14769677

Updated 3-Dec-21 10:38am

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Stefan_Lang · Answer 1 · 2021-12-03T09:18:00

You're creating iterators that point past the array after you've erased the first elements! Trying to erase invalid iterators then crashes the program.

You need to make sure that pos actually is a valid index at the time when you call erase!

Example:
if newArr has 2 elements, and your loop iterates from 0 to 1, then the first iteration will erase the first element, move the element at position 1 to position 0, and reduce the size of the array from 2 to 1. In the second iteration, you try to erase an element at position 1, but that is now past the end of the vector!

P.S.: the safe way to erase multiple elements from a vector is starting with the highest position, not the lowest. Alternately, if you wish to erase a range of elements, I believe there is an overload for erase that accepts a range start and range end.

CPallini · Answer 2 · 2021-12-03T10:38:00

Solution 2

As Stefan suggested, you may use the erase overload that takes a range (two iterators) as argument. See the code sample here: vector::erase - C++ Reference[^].

Posted 3-Dec-21 10:38am

CPallini

Updated 3-Dec-21 10:39am

v2