Книга: Standard Template Library Programmer

is_sorted

is_sorted

Category: algorithms

Component type: function

Is_sorted is an overloaded name; there are actually two is_sorted functions.

template <class ForwardIterator>
bool is_sorted(ForwardIterator first, ForwardIterator last)
template <class ForwardIterator, class StrictWeakOrdering>
bool is_sorted(ForwardIterator first, ForwardIterator last, StrictWeakOrdering comp)

Is_sorted returns true if the range [first, last) is sorted in ascending order, and false otherwise.

The two versions of is_sorted differ in how they define whether one element is less than another. The first version compares objects using operator< , and the second compares objects using the function object comp. The first version of is_sorted returns true if and only if, for every iterator i in the range [first, last – 1), *(i + 1) < *i is false. The second version returns true if and only if, for every iterator i in the range [first, last – 1), comp(*(i + 1), *i) is false.

Defined in algo.h.

For the first version:

• ForwardIterator is a model of Forward Iterator.

• ForwardIterator's value type is a model of LessThan Comparable.

• The ordering on objects of ForwardIterator's value type is a strict weak ordering, as defined in the LessThan Comparable requirements.

For the second version:

• ForwardIterator is a model of Forward Iterator.

• StrictWeakOrdering is a model of Strict Weak Ordering.

• ForwardIterator's value type is convertible to StrictWeakOrdering's argument type.

• [first, last) is a valid range.

Linear. Zero comparisons if [first, last) is an empty range, otherwise at most (last – first) – 1 comparisons.

int A[] = {1, 4, 2, 8, 5, 7};
const int N = sizeof(A) / sizeof(int);
assert(!is_sorted(A, A + N));
sort(A, A + N);
assert(is_sorted(A, A + N));

sort, stable_sort, partial_sort, partial_sort_copy, sort_heap, binary_search, lower_bound, upper_bound, less<T>, StrictWeakOrdering, LessThan Comparable

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