std::equal

 

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正则表达式库 （C++11）

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算法库

功能 Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
修改序列操作 Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of （C++11） （C++11） （C++11） for_each count count_if mismatch equal	find find_if find_if_not （C++11） find_end find_first_of adjacent_find search search_n
修改序列操作 Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if （C++11） copy_n （C++11） copy_backward move （C++11） move_backward （C++11） fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   （C++11） unique unique_copy
分区操作 Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned （C++11） partition partition_copy （C++11）	stable_partition partition_point （C++11）
排序操作（排序的区间） Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted （C++11） is_sorted_until （C++11） sort	partial_sort partial_sort_copy stable_sort nth_element
二进制搜索操作（排序的区间） Original: Binary search operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lower_bound upper_bound	binary_search equal_range
设置操作（排序的区间） Original: Set operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
堆的操作 Original: Heap operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_heap is_heap_until （C++11） make_heap	push_heap pop_heap sort_heap
最小/最大操作 Original: Minimum/maximum operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
max max_element min min_element minmax （C++11） minmax_element （C++11）	lexicographical_compare is_permutation （C++11） next_permutation prev_permutation
数字操作 Original: Numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
iota （C++11） accumulate inner_product	adjacent_difference partial_sum
C库 Original: C library The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
qsort	bsearch

 

Defined in header <algorithm>
template< class InputIt1, class InputIt2 > bool equal( InputIt1 first1, InputIt1 last1,             InputIt2 first2 );	(1)
template< class InputIt1, class InputIt2, class BinaryPredicate > bool equal( InputIt1 first1, InputIt1 last1,             InputIt2 first2, BinaryPredicate p );	(2)

返回true如果元素是相同的，在两个范围：1所定义[first1, last1)和另一个开始first2。 operator==的第一个版本的功能使用比较的元素，第二个使用给定的二元谓词p.

Original:

Returns true if the elements are the same in two ranges: one defined by [first1, last1) and another starting at first2. The first version of the function uses operator== to compare the elements, the second uses the given binary predicate p.

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参数

first1, last1	-	第一范围的元素进行比较 Original: the first range of the elements to compare The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
first2	-	开始的第二范围的元素进行比较 Original: beginning of the second range of the elements to compare The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
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: bool pred(const Type1 &a, const Type2 &b); The signature does not need to have const &, but the function must not modify the objects passed to it. The types  Type1 and  Type2 must be such that objects of types InputIt1 and InputIt2 can be dereferenced and then implicitly converted to  Type1 and  Type2 respectively. ​
Type requirements
- InputIt1, InputIt2 must meet the requirements of InputIterator.

返回值

true如果这两个范围中的元素是相等的

Original:

true if the elements in the two ranges are equal

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注释

std::equal不得用于比较的范围所形成的迭代器从std::unordered_set，std::unordered_multiset，std::unordered_map或std::unordered_multimap因为被存储在这些容器中的元素的顺序可以是不同的，即使在两个容器存储相同的元件.

Original:

std::equal may not be used to compare the ranges formed by the iterators from std::unordered_set, std::unordered_multiset, std::unordered_map, or std::unordered_multimap because the order in which the elements are stored in those containers may be different even if the two containers store the same elements.

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{{{1}}}

Original:

{{{2}}}

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复杂性

在最last1 - first1谓词的应用

Original:

At most last1 - first1 applications of the predicate

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可能的实现

First version
template<class InputIt1, class InputIt2> bool equal(InputIt1 first1, InputIt1 last1, InputIt2 first2) { for (; first1 != last1; ++first1, ++first2) { if (!(*first1 == *first2)) { return false; } } return true; }
Second version
template<class InputIt1, class InputIt2, class BinaryPredicate> bool equal(InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryPredicate p) { for (; first1 != last1; ++first1, ++first2) { if (!p(*first1, *first2)) { return false; } } return true; }

为例

下面的代码使用equal()来测试一个字符串是否是回文

Original:

The following code uses equal() to test if a string is a palindrome

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#include <iostream>
#include <algorithm>
#include <string>
 
void test(const std::string& s)
{
    if(std::equal(s.begin(), s.begin() + s.size()/2, s.rbegin())) {
        std::cout << "\"" << s << "\" is a palindrome\n";
    } else {
        std::cout << "\"" << s << "\" is not palindrome\n";
    }
}
int main()
{
    test("radar");
    test("hello");
}

Output:

"radar" is a palindrome
"hello" is not palindrome

find find_if find_if_not （C++11）	找到的第一个元素，满足特定的标准 Original: finds the first element satisfying specific criteria The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）
lexicographical_compare	返回true，如果一个范围是小于另一个字典 Original: returns true if one range is lexicographically less than another The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）
mismatch	发现两个范围不同的第一位置 Original: finds the first position where two ranges differ The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）
search	searches for a range of elements （函数模板）