使用LINQ如何分割字符串（不是在字符上而是在索引上）

Question

I wanted to split a string

Input :

ABCDEFGHI

Output :

ABC, DEF, GHI

One way is by using For Loop.

string str = "ABCDEFGHI";

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

string temp = "";

for(int i = 0; i < str.Length; i++)
{
    temp = str[i].Tostring();

    if((i + 1) % 3 == 0)
    {
        lst.Add(temp);
        temp = "";
    }
}

string final_str = string.Join(", ", lst);

But how to do that using LINQ ?

Answer 1

var str = "ABCDEFGHI";

var result = testStr.Select(s => testStr.IndexOf(s))
                   .Where(i => i%3 == 0)
                   .Select(i => testStr.Substring(i,3))
                   .Aggregate("", (a,s) => a += s + ",");

Answer 2

在MoreLinq的帮助下

List<string> lst = str.Batch(3).Select(s => String.Join("",s)).ToList();

Answer 3

And another one ( without MoreLinq ):

var str = "ABCDEFGHI";
var tmp = str.Select((i, index) => new { i, index })
             .GroupBy(g => g.index / 3, e => e.i)
             .Select(g => String.Join("", g));
var final_string = String.Join(", ", tmp);

Answer 4

using MoreLinq.Batch

var result = str.Batch(3);

type of result is IEnumerable>, ToArray can be used to make it IEnumerable< char[] >

EDIT I forgot last join statement in the first glance

var finalStr = String.Join(",",str.Batch(3).Select(x=>new String(x.ToArray())))

Answer 5

String.Join("", str.Select((x, i) => (i + 1)%3 == 0 ? x + " " : x.ToString()))