function template
<algorithm>
std::none_of
template <class InputIterator, class UnaryPredicate>
bool none_of (InputIterator first, InputIterator last, UnaryPredicate pred);
Test if no elements fulfill condition
Returns true
if pred returns false
for all the elements in the range [first,last)
or if the range is empty, and false
otherwise.
The behavior of this function template is equivalent to:
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template<class InputIterator, class UnaryPredicate>
bool none_of (InputIterator first, InputIterator last, UnaryPredicate pred)
{
while (first!=last) {
if (pred(*first)) return false;
++first;
}
return true;
}
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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 false
for all the elements in the range [first,last)
or if the range is empty, and false
otherwise.
Example
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// none_of example
#include <iostream> // std::cout
#include <algorithm> // std::none_of
#include <array> // std::array
int main () {
std::array<int,8> foo = {1,2,4,8,16,32,64,128};
if ( std::none_of(foo.begin(), foo.end(), [](int i){return i<0;}) )
std::cout << "There are no negative elements in the range.\n";
return 0;
}
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Output:
There are no negative elements in the range.
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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.
See also
- all_of
- Test condition on all elements in range (function template
)
- any_of
- Test if any element in range fulfills condition (function template
)
- find_if_not
- Find element in range (negative condition) (function template
)