How to Safely Erase Elements from a C Vector While Iterating?

Vector Eradication with Erasing Iterators

In programming, traversing and manipulating data structures efficiently is crucial. Vectors, a popular dynamic container in C , provide flexibility and growth capabilities. However, erasing elements while iterating them can lead to unexpected outcomes.

Consider this example:

int main()
{
    vector<int> res;
    res.push_back(1);
    vector<int>::iterator it = res.begin();
    for( ; it != res.end(); it++)
    {
        it = res.erase(it);
        //if(it == res.end())
        //  return 0;
    }
}

The code above aims to erase all elements from the vector 'res' while iterating through it. However, it encounters an error when erasing the last element. This is because the iterator returned by 'res.erase(it)' points to the next valid element, which would be 'res.end()' in this case.

To resolve this issue, one can use a while loop without the conditional statement, like:

while (it != res.end()) {
    it = res.erase(it);
}

This ensures that the loop continues until all elements have been erased.

Alternatively, if you only need to erase specific elements based on some condition, you can use the following approach:

for ( ; it != res.end(); ) {
  if (condition) {
    it = res.erase(it);
  } else {
    ++it;
  }
}

Remember, when using iterators for vector manipulation, it's vital to understand how 'res.erase(it)' operates and to adjust the loop accordingly to prevent unexpected behaviors.

The above is the detailed content of How to Safely Erase Elements from a C Vector While Iterating?. For more information, please follow other related articles on the PHP Chinese website!