| Defined in header <algorithm> | ||
|---|---|---|
template< class ForwardIt1, class ForwardIt2 >
ForwardIt1 search( ForwardIt1 first, ForwardIt1 last,
ForwardIt2 s_first, ForwardIt2 s_last ); | (1) | |
template< class ForwardIt1, class ForwardIt2, class BinaryPredicate >
ForwardIt1 search( ForwardIt1 first, ForwardIt1 last,
ForwardIt2 s_first, ForwardIt2 s_last, BinaryPredicate p ); | (2) |
Searches for the first occurrence of the subsequence of elements [s_first, s_last) in the range [first, last - (s_last - s_first)). The first version uses operator== to compare the elements, the second version uses the given binary predicate p.
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 |
| Type requirements | ||
- ForwardIt1, ForwardIt2 must meet the requirements of ForwardIterator. | ||
Return value
Iterator to the beginning of first subsequence [s_first, s_last) in the range [first, last - (s_last - s_first)). If no such subsequence is found, last is returned.
If [s_first, s_last) is empty, first is returned. (since C++11).
Complexity
At most S*N comparisons where S = std::distance(s_first, s_last) and N = std::distance(first, last).
Possible implementation
| First version |
|---|
template<class ForwardIt1, class ForwardIt2>
ForwardIt1 search(ForwardIt1 first, ForwardIt1 last,
ForwardIt2 s_first, ForwardIt2 s_last)
{
for (; ; ++first) {
ForwardIt1 it = first;
for (ForwardIt2 s_it = s_first; ; ++it, ++s_it) {
if (s_it == s_last) {
return first;
}
if (it == last) {
return last;
}
if (!(*it == *s_it)) {
break;
}
}
}
} |
| Second version |
template<class ForwardIt1, class ForwardIt2, class BinaryPredicate>
ForwardIt1 search(ForwardIt1 first, ForwardIt1 last,
ForwardIt2 s_first, ForwardIt2 s_last,
BinaryPredicate p)
{
for (; ; ++first) {
ForwardIt1 it = first;
for (ForwardIt2 s_it = s_first; ; ++it, ++s_it) {
if (s_it == s_last) {
return first;
}
if (it == last) {
return last;
}
if (!p(*it, *s_it)) {
break;
}
}
}
} |
Example
#include <string>
#include <algorithm>
#include <iostream>
#include <vector>
template<typename Container>
bool in_quote(const Container& cont, const std::string& s)
{
return std::search(cont.begin(), cont.end(), s.begin(), s.end()) != cont.end();
}
int main()
{
std::string str = "why waste time learning, when ignorance is instantaneous?";
// str.find() can be used as well
std::cout << std::boolalpha << in_quote(str, "learning") << '\n'
<< in_quote(str, "lemming") << '\n';
std::vector<char> vec(str.begin(), str.end());
std::cout << std::boolalpha << in_quote(vec, "learning") << '\n'
<< in_quote(vec, "lemming") << '\n';
}Output:
true false true false
See also
| finds the last sequence of elements in a certain range (function template) | |
| returns true if one set is a subset of another (function template) | |
| determines if two sets of elements are the same (function template) | |
| (C++11) | finds the first element satisfying specific criteria (function template) |
| returns true if one range is lexicographically less than another (function template) | |
| finds the first position where two ranges differ (function template) | |
| searches for a number consecutive copies of an element in a range (function template) | |
| std::experimental::search
(library fundamentals TS) | applies a searcher to a sequence (function template) |
| std::experimental::parallel::search
(parallelism TS) | parallelized version of std::search (function template) |
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