Swift 2 计算数组匹配条件的元素 [英] Swift 2 Count elements of array matching condition

问题描述

我基本上是在寻找以下 C++ 代码的 swift 等效项:

I'm basically looking for the swift equivalent of the follow c++ code:

std::count_if(list.begin(), list.end(), [](int a){ return a % 2 == 0; }); // counts instances of even numbers in list

当然，我的问题实际上并不是搜索偶数；简单地统计匹配一个标准的实例的一般情况.

My problem isn't actually searching for even numbers, of course; simply the general case of counting instances matching a criterion.

我还没有看到内置函数，但很想知道我只是错过了它.

I haven't seen a builtin, but would love to hear that I simply missed it.

推荐答案

像这样:

 let a: [Int] = ...
 let count = a.filter({ $0 % 2 == 0 }).count

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