std::vector erase() method

since C++20

// prism-push-types:iterator,const_iterator
// (1) Non const version only
constexpr iterator erase( const_iterator pos );

// (2) Non const version only
constexpr iterator erase( const_iterator first, const_iterator last );

since C++11

// prism-push-types:iterator,const_iterator
// (1) Non const version only
iterator erase( const_iterator pos );

// (2) Non const version only
iterator erase( const_iterator first, const_iterator last );

until C++11

// prism-push-types:iterator,const_iterator
// (1) Non const version only
iterator erase( iterator pos );

// (2) Non const version only
iterator erase( iterator first, iterator last );

Erases the specified elements from the container.

• (1) Removes the element at pos.
• (2) Removes the elements in the range [ first, last ).

Invalidation

Invalidates iterators and references at or after the point of the erase, including the end() iterator.

Using past-the-end iteraotr

The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos.

The iterator first does not need to be dereferenceable if first == last: erasing an empty range is a no-op.

Parameters

• pos - itertor to the element to remove
• first, last - range of elements to remove

Type requirements

• T (the container's element type) must meet the requirements of MoveAssignable.

Return value

Iterator following the last removed element.

• If pos refers to the last element, then the end() iterator is returned.
• If last == end() prior to removal, then the updated end() iterator is returned.
• If [ first, last ) is an empty range, then last is returned.

Complexity

Linear: the number of calls to the destructor of T is the same as the number of elements erased, the assignment operator of T is called the number of times equal to the number of elements in the vector after the erased elements.

Exceptions

Does not throw unless an exception is thrown by the assignment operator of T.

Notes

If value-initialization in overload (1) is undesirable, for example, if the elements are of non-class type and zeroing out is not needed,

it can be avoided by providing a custom Allocator::construct(). Vector capacity is never reduced when resizing to smaller size because that would invalidate all iterators, rather than only the ones that would be invalidated by the equivalent sequence of pop_back() calls.

Example

Main.cpp

#include <vector>
#include <iostream>
 
 
void print_container(const std::vector<int>& c) 
{
    for (int i : c) {
        std::cout << i << " ";
    }
    std::cout << '\n';
}
 
int main( )
{
    std::vector<int> c{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    print_container(c);
 
    c.erase(c.begin());
    print_container(c);
 
    c.erase(c.begin()+2, c.begin()+5);
    print_container(c);
 
    // Erase all even numbers (C++11 and later)
    for (std::vector<int>::iterator it = c.begin(); it != c.end(); ) {
        if (*it % 2 == 0) {
            it = c.erase(it);
        } else {
            ++it;
        }
    }
    print_container(c);
}

Output

0 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 6 7 8 9
1 7 9