STL算法全部还是任何功能？ [英] STL algorithm all or any function?

问题描述

有什么近似Haskell的所有或任何功能作为STL的一部分？如果没有，是下面一个很好的实现（我注意到sgi STL执行部分专门化，如果迭代器是随机访问，虽然我没有打扰这）。

Is there anything approximating Haskell's all or any functions as part of the STL? If not, is the below a good implementation (I noticed the sgi STL performed partial specialization if the iterators were random access, though I have not bothered with this)?

template <typename InputIterator, typename Predicate>
inline bool all(InputIterator first, InputIterator last, Predicate pred) {
  while (first != last) {
    if (!pred(*first)) {
      return false;
    }
    ++first;
  }
  return true;
}

$ b <其中BinaryPredicate对所有返回true，否则为false？我知道这是相对微不足道，但似乎这应该由算法提供，我想确保我不会忽视的东西。

Similarly, how would this best be transformed to iterate two sequences, and return true where a BinaryPredicate returns true for all, and false otherwise? I know this is relatively trivial, but it seems like this should be provided by algorithm, and I want to make sure I'm not overlooking something.

推荐答案

目前C ++中没有 all 或任何算法， C ++标准库的code> std :: all_of 和 std :: any_of 算法。

There are not all or any algorithms in C++ currently, but C++0x adds std::all_of and std::any_of algorithms to the C++ standard library. Your implementation may support these already.

由于这两个算法都需要测试范围内的所有元素（至少直到找到匹配或不匹配），因此，任何原因使它们专门用于不同类型的迭代器：使用前向迭代器时的性能应与使用随机访问迭代器时的性能相同。

Since both of these algorithms need to test every element in the range (at least until they find a match or mismatch), there isn't any reason to specialize them for different types of iterators: the performance when used with forward iterators should be the same as the performance when used with random access iterators.

all 是罚款; Visual C ++ all_of 实现是完全相同的，除了它使用for循环而不是while循环。

Your implementation of all is fine; the Visual C++ all_of implementation is effectively the same, except that it uses a for loop instead of a while loop.

如何最好地转换为迭代两个序列，并返回true，其中BinaryPredicate为所有返回true，否则返回false？

how would this best be transformed to iterate two sequences, and return true where a BinaryPredicate returns true for all, and false otherwise?

这是 std :: equal 的用法。您需要先检查范围的大小，以确保它们的大小相同。

This is what std::equal does. You'll need to check the sizes of the ranges first to ensure that they are of the same size.

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