Question

从LINQ Quiz问题和答案到Q4和Q5

将colors数组定义为：

string[] colors = { "green", "brown", "blue", "red" };

并从答案到Q4查询：

var query =
  from c in colors
  where c.Length == colors.Max (c2 => c2.Length)
  select c;

我是否正确理解外部查询迭代表达式c2.Length将被评估16次？

即，对于с数组中的每个项colors，colors.Max (c2 => c2.Length)将被评估一次，即Max()计算将完成4次。对于每次Max()评估，c2.Length将被找到4次？

Answer 1

是的，这是正确的。如果您有LINQPad尝试，也很容易检查：

string[] colors = { "green", "brown", "blue", "red" };

int count = 0;

var query =
    from c in colors
    where c.Length == colors.Max (c2 => 
        {
            count.Dump();
            count++;
            return c2.Length;
        }
    )
    select c;

query.Dump();

lambda外子查询迭代变量计算的数量

1 个答案: