std::find_if_not

template <class InputIterator, class UnaryPredicate>   InputIterator find_if_not (InputIterator first, InputIterator last, UnaryPredicate pred);

Find element in range (negative condition)

Returns an iterator to the first element in the range [first,last) for which pred returns false. If no such element is found, the function returns last.

The behavior of this function template is equivalent to:

template<class InputIterator, class UnaryPredicate>
  InputIterator find_if_not (InputIterator first, InputIterator last, UnaryPredicate pred)
{
  while (first!=last) {
    if (!pred(*first)) return first;
    ++first;
  }
  return last;
}

Parameters

first, last: Input iterators to the initial and final positions in a sequence. The range used is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
pred: Unary function that accepts an element in the range as argument and returns a value convertible to bool. The value returned indicates whether the element is considered a match in the context of this function.
The function shall not modify its argument.
This can either be a function pointer or a function object.

Return value

An iterator to the first element in the range for which pred returns false.
If pred is true for all elements, the function returns last.

Example

// find_if_not example
#include <iostream>     // std::cout
#include <algorithm>    // std::find_if_not
#include <array>        // std::array

int main () {
  std::array<int,5> foo = {1,2,3,4,5};

  std::array<int,5>::iterator it =
    std::find_if_not (foo.begin(), foo.end(), [](int i){return i%2;} );
  std::cout << "The first even value is " << *it << '\n';

  return 0;
}

Output:

The first even value is 2

Complexity

Up to linear in the distance between first and last: Calls pred for each element until a mismatch is found.

Data races

Some (or all) of the objects in the range [first,last) are accessed (once at most).

Exceptions

Throws if either pred or an operation on an iterator throws.
Note that invalid parameters cause undefined behavior.