C++11新特性应用--介绍几个新增的便利算法(不更改容器中元素顺序的算法)

总所周知。C++ STL中有个头文件，名为algorithm。即算法的意思。

The header<algorithm>defines a collection of functions especially designed to be used on ranges of elements.

所以，要八一八这个头文件里C++11新增的几个算法，今天主要描写叙述的几个算法不改变容器中元素的顺序。

这里还要啰嗦一句，使用stl算法时，假设与lambda表达式组合使用，那么代码会更加简洁。

find_if_not
该算法在之前介绍过，请參阅博客《实战c++中的vector系列–vector应用之STL的find、find_if、find_end、find_first_of、find_if_not(C++11)》。

all_of
原型：

template <class InputIterator, class UnaryPredicate>
  bool all_of (InputIterator first, InputIterator last, UnaryPredicate pred);

作用：
Test condition on all elements in range
Returns true if pred returns true for all the elements in the range [first,last) or if the range is empty, and false otherwise.
检測区间[first, last)中是否全部的元素都满足一元推断表达式pred。全部的元素都满足条件返回true，否则返回false.

应用：

#include <iostream>     // std::cout
#include <algorithm>    // std::all_of
#include <array>        // std::array

int main () {
  std::array<int,8> foo = {3,5,7,11,13,17,19,23};

  if ( std::all_of(foo.begin(), foo.end(), [](int i){return i%2;}) )
    std::cout << "All the elements are odd numbers.
";

  return 0;
}
//输出：
All the elements are odd numbers.

any_of
原型：

template <class InputIterator, class UnaryPredicate>
  bool any_of (InputIterator first, InputIterator last, UnaryPredicate pred);

作用：
Test if any element in range fulfills condition
Returns true if pred returns true for any of the elements in the range [first,last), and false otherwise.

应用：

#include <iostream>     // std::cout
#include <algorithm>    // std::any_of
#include <array>        // std::array

int main () {
  std::array<int,7> foo = {0,1,-1,3,-3,5,-5};

  if ( std::any_of(foo.begin(), foo.end(), [](int i){return i<0;}) )
    std::cout << "There are negative elements in the range.
";

  return 0;
}
//输出：
There are negative elements in the range.

none_of
原型：

template <class InputIterator, class UnaryPredicate>
  bool none_of (InputIterator first, InputIterator last, UnaryPredicate pred);

作用：
Returns true if pred returns false for all the elements in the range [first,last) or if the range is empty, and false otherwise.

应用：

#include <iostream>     // std::cout
#include <algorithm>    // std::none_of
#include <array>        // std::array

int main () {
  std::array<int,8> foo = {1,2,4,8,16,32,64,128};

  if ( std::none_of(foo.begin(), foo.end(), [](int i){return i<0;}) )
    std::cout << "There are no negative elements in the range.
";

  return 0;
}
//输出：
There are no negative elements in the range.

is_permutation
permutation 名词 排列 、交换等意思。

该函数是用来推断两个序列是否为同一元素集的不同排列。
该函数使用operator==或者是pred来推断两个元素是否是相等的。

原型：

template <class ForwardIterator1, class ForwardIterator2>
   bool is_permutation (ForwardIterator1 first1, ForwardIterator1 last1,
                        ForwardIterator2 first2);   
template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
   bool is_permutation (ForwardIterator1 first1, ForwardIterator1 last1,
                        ForwardIterator2 first2, BinaryPredicate pred);

作用：
Test whether range is permutation of another
Compares the elements in the range [first1,last1) with those in the range beginning at first2, and returns true if all of the elements in both ranges match, even in a different order.

应用：

#include <iostream>     // std::cout
#include <algorithm>    // std::is_permutation
#include <array>        // std::array

int main () {
  std::array<int,5> foo = {1,2,3,4,5};
  std::array<int,5> bar = {3,1,4,5,2};

  if ( std::is_permutation (foo.begin(), foo.end(), bar.begin()) )
    std::cout << "foo and bar contain the same elements.
";

  return 0;
}
//输出：
foo and bar contain the same elements.

这里须要注意的是。你不能突发奇想，比方用大于号或是小于号进行比較，你仅仅能这样：
The elements are compared using operator== (or pred）