在for_each期间从设置擦除C ++元素

Question

Is it legal to erase an element from a set while doing for_each over the set, as long as you don't remove the current item?

Set erase keeps all iterators valid except the one being erased.

For example:

set<int> nums{0, 1, 2, 3, 4};

void weird_remove(int x) {
    int randnum = rand() % 5;
    if (randnum != x) {
        nums.erase(randnum);
    }
}

int main() {
    for_each(nums.begin(), nums.end(), weird_remove);
}

Also how about during range for loops?

And I assume the answers apply to map as well as set.

Answer 1

Question:

Is it legal to erase an element from a set while doing for_each over the set , as long as you don't remove the current item?

Yes, it is legal.

From http://en.cppreference.com/w/cpp/container/set/erase :

size_type erase( const key_type& key ); (3)

Removes specified elements from the container.
3) Removes all elements with the key value key.

References and iterators to the erased elements are invalidated. Other references and iterators are not affected.