std::any_of

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

Test if any element in range fulfills condition

Returns true if pred returns true for any of the elements in the range [first,last), and false otherwise.

If [first,last) is an empty range, the function returns false.

The behavior of this function template is equivalent to:

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

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 fulfills the condition checked by this function.
The function shall not modify its argument.
This can either be a function pointer or a function object.

Return value

true if pred returns true for any of the elements in the range [first,last), and false otherwise.

If [first,last) is an empty range, the function returns false.

Example

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

int main () {
  std::array<int,7> foo = {0,1,-1,3,-3,5,-5};

  if ( std::any_of(foo.begin(), foo.end(), [](int i){return i<0;}) )
    std::cout << "There are negative elements in the range.\n";

  return 0;
}

Output:

There are negative elements in the range.

Complexity

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