How do I remove an item from a stl vector with a certain value?

If you want to remove an item, the following will be a bit more efficient.

std::vector<int> v;


auto it = std::find(v.begin(), v.end(), 5);
if(it != v.end())
    v.erase(it);

or you may avoid overhead of moving the items if the order does not matter to you:

std::vector<int> v;

auto it = std::find(v.begin(), v.end(), 5);

if (it != v.end()) {
  using std::swap;

  // swap the one to be removed with the last element
  // and remove the item at the end of the container
  // to prevent moving all items after '5' by one
  swap(*it, v.back());
  v.pop_back();
}

Use the global method std::remove with the begin and end iterator, and then use std::vector.erase to actually remove the elements.

Documentation links
std::remove http://www.cppreference.com/cppalgorithm/remove.html
std::vector.erase http://www.cppreference.com/cppvector/erase.html

std::vector<int> v;
v.push_back(1);
v.push_back(2);

//Vector should contain the elements 1, 2

//Find new end iterator
std::vector<int>::iterator newEnd = std::remove(v.begin(), v.end(), 1);

//Erase the "removed" elements.
v.erase(newEnd, v.end());

//Vector should now only contain 2

Thanks to Jim Buck for pointing out my error.

std::remove does not actually erase elements from the container: it moves the elements to be removed to the end of the container, and returns the new end iterator which can be passed to container_type::erase to do the actual removal of the extra elements that are now at the end of the container:

std::vector<int> vec;
// .. put in some values ..
int int_to_remove = n;
vec.erase(std::remove(vec.begin(), vec.end(), int_to_remove), vec.end());