std::find_first_of
From Cppreference
| Defined in header
<algorithm> | ||
| template< class ForwardIterator1, class ForwardIterator2 >
ForwardIterator1 find_first_of( ForwardIterator1 first, ForwardIterator1 last, | (1) | |
| template< class ForwardIterator1, class ForwardIterator2, class BinaryPredicate >
ForwardIterator1 find_first_of( ForwardIterator1 first, ForwardIterator1 last, | (2) | |
Searches the range [first, last) for any of the elements in the range [s_first, s_last). The first version uses operator== to compare the elements, the second version uses the given binary predicate p.
Contents |
Parameters
| first, last | - | the range of elements to examine | |||||||||
| s_first, s_last | - | the range of elements to search for | |||||||||
| p | - | binary predicate which returns true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:
The signature does not need to have const &, but the function must not modify the objects passed to it. | |||||||||
Return value
iterator to the first element in the range [first, last) that is equal to an element from the range [s_first; s_last). If no such element is found, last is returned.
Complexity
does at most S*N) comparisons where S = distance(s_first, s_last) and N = distance(first, last).
Equivalent function
| First version: |
|---|
template<class ForwardIterator1, class ForwardIterator2> ForwardIterator1 find_first_of(ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last) { for (; first != last; ++first) { for (ForwardIterator2 it = sfirst; it != s_last; ++it) { if (*first == *it) { return first; } } } return last; } |
| Second version: |
template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate> ForwardIterator1 find_first_of(ForwardIterator1 first, ForwardIterator1 last, ForwardIterator2 s_first, ForwardIterator2 s_last, BinaryPredicate p) { for (; first != last; ++first) { for (ForwardIterator2 it = sfirst; it != s_last; ++it) { if (p(*first, *it)) { return first; } } } return last; } |
Example
The following code searches for a 9, 4, or 7 in an array of integers:
#include <algorithm> #include <iostream> int main() { int nums[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; int* result; int end = 10; int targets[] = { 9, 4, 7 }; int target_end; result = std::find_first_of(nums, nums + end, targets, targets + targets_end); if (*result == nums[end]) { std::cout << "any of { 9, 4, 7 } not found"; } else { std::cout << "found a match at " << result - nums; } return 0; }
Output:
found a match at 4
See also
| finds the first element satisfying specific criteria (function template) | ||
