You’ll see from the output that with the unstable partition, the objects are correctly above and below the partition point, but in no particular order; whereas with the stable partition, their original order is maintained.
Searching and replacing
All these algorithms are used for searching for one or more objects within a range defined by the first two iterator arguments.
InputIterator find(InputIterator first, InputIterator last, const EqualityComparable& value);
Searches for value within a range of elements. Returns an iterator in the range [first, last) that points to the first occurrence of value. If value isn’t in the range, find( ) returns last. This is a linear search; that is, it starts at the beginning and looks at each sequential element without making any assumptions about the way the elements are ordered. In contrast, a binary_search( ) (defined later) works on a sorted sequence and can thus be much faster.
InputIterator find_if(InputIterator first, InputIterator last, Predicate pred);
Just like find( ), find_if( ) performs a linear search through the range. However, instead of searching for value, find_if( ) looks for an element such that the Predicate pred returns true when applied to that element. Returns last if no such element can be found.
ForwardIterator adjacent_find(ForwardIterator first, ForwardIterator last); ForwardIterator adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate binary_pred);
Like find( ), performs a linear search through the range, but instead of looking for only one element, it searches for two adjacent elements that are equivalent. The first form of the function looks for two elements that are equivalent (via operator==). The second form looks for two adjacent elements that, when passed together to binary_pred, produce a true result. An iterator to the first of the two elements is returned if a pair is found; otherwise, last is returned.
ForwardIterator1 find_first_of(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2); ForwardIterator1 find_first_of(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate binary_pred);.
Like find( ), performs a linear search through the range. Both forms search for an element in the second range that’s equivalent to one in the first, the first form using operator==, and the second using the supplied predicate. In the second form, the current element from the first range becomes the first argument to binary_pred, and the element from the second range becomes the second argument.
ForwardIterator1 search(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2); ForwardIterator1 search(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2 BinaryPredicate binary_pred);
Checks to see if the second range occurs (in the exact order of the second range) within the first range, and if so returns an iterator pointing to the place in the first range where the second range begins. Returns last1 if no subset can be found. The first form performs its test using operator==, and the second checks to see if each pair of objects being compared causes binary_pred to return true.
ForwardIterator1 find_end(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2); ForwardIterator1 find_end(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate binary_pred);
The forms and arguments are just like search( ) in that they look for the second range appearing as a subset of the first range, but while search( ) looks for the first occurrence of the subset, find_end( ) looks for the last occurrence and returns an iterator to its first element.
ForwardIterator search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value); ForwardIterator search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value, BinaryPredicate binary_pred);
Looks for a group of count consecutive values in [first, last) that are all equal to value (in the first form) or that all cause a return value of true when passed into binary_pred along with value (in the second form). Returns last if such a group cannot be found.
ForwardIterator min_element(ForwardIterator first, ForwardIterator last); ForwardIterator min_element(ForwardIterator first, ForwardIterator last, BinaryPredicate binary_pred);
Returns an iterator pointing to the first occurrence of the "smallest" value in the range (as explained below—there may be multiple occurrences of this value.) Returns last if the range is empty. The first version performs comparisons with operator<, and the value r returned is such that *e < *r is false for every element e in the range [first, r). The second version compares using binary_pred, and the value r returned is such that binary_pred (*e, *r) is false for every element e in the range [first, r).
ForwardIterator max_element(ForwardIterator first, ForwardIterator last); ForwardIterator max_element(ForwardIterator first, ForwardIterator last, BinaryPredicate binary_pred);
Returns an iterator pointing to the first occurrence of the largest value in the range. (There may be multiple occurrences of the largest value.) Returns last if the range is empty. The first version performs comparisons with operator<, and the value r returned is such that *r < *e is false for every element e in the range [first, r). The second version compares using binary_pred, and the value r returned is such that binary_pred (*r, *e) is false for every element e in the range [first, r).
void replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value); void replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const T& new_value); OutputIterator replace_copy(InputIterator first, InputIterator last, OutputIterator result, const T& old_value, const T& new_value); OutputIterator replace_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred, const T& new_value);
Each of the "replace" forms moves through the range [first, last), finding values that match a criterion and replacing them with new_value. Both replace( ) and replace_copy( ) simply look for old_value to replace; replace_if( ) and replace_copy_if( ) look for values that satisfy the predicate pred. The "copy" versions of the functions do not modify the original range but instead make a copy with the replacements into result (incrementing result after each assignment).