总和列表中的一个INT范围[英] Sum a range of ints in a List

问题描述

Let's say I have a List like this:

List<string> _lstr = new List<string>();

        _lstr.Add("AA");
        _lstr.Add("BB");
        _lstr.Add("1");
        _lstr.Add("7");
        _lstr.Add("2");
        _lstr.Add("5");

How do I sum up the integers in the List if I don't know how many integers are in the List? Could be 4, could be 10, etc... All I know is that the first two items are strings, the rest are integers.

In this case the desired result is 15.

推荐答案

Method A Unconditionally skips the first 2 and assumes the rest are all integer strings:

var sum = _lstr.Skip(2).Select(int.Parse).Sum();

Method B Makes no assumtions:

var sum = _lstr.Aggregate(0, (x, z) => x + (int.TryParse(z, out x) ? x : 0));

其他推荐答案

without making the assumption that first two items are strings

int sum = _lstr.Select(s => {int i; return int.TryParse(s,out i) ? i : 0; })
               .Sum();

其他推荐答案

Very easily:

list.Skip(2).Select(int.Parse).Sum();