Where is erase_if?

Question

I've got a container and would like to erase elements based on a predicate. Erase_if sounds familiar, but I can't find it in C++. What's the name and where is it defined? I'd like to use it with a lambda in VS10.

Answer 1

I believe that you want remove_if

Answer 2

You're probably looking for std::remove_if, in a pattern such as:

vec.erase(std::remove_if(vec.begin(), vec.end(), predicate), vec.end());

Answer 3

There is a list::remove_if, but not for all container classes. remove_if also exists as a algorithm, which can be used with the iterators you can get from begin() and end().

Answer 4

I'm guessing you're thinking of remove_if which takes a predicate to determine if the element ought to be removed.

remove_if returns an iterator pointing to the beginning of the elements to remove in the container. To actually remove them you need to use erase:

container.erase(remove_if(container.start(), container.end(), pred), container.end())

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Either that or perhaps you mistakenly recalled the copy_if algorithm? Which somehow got left out of the standard but was written about - and implemented - in Effective STL.