如何将八个字符串分成四个变量？

Question

I hava a string like this:

var id = "01020304";

Is there a simple way I can split this into four variables called pr, pa, fo, it Each variable needs to have the two characters of the string. Looking for an elegant solution if it exists.

Answer 1

You can use Substring :

pr = id.Substring(0, 2);
pa = id.Substring(2, 2);
fo = id.Substring(4, 2);
it = id.Substring(6, 2);

Answer 2

Since you have four distinct variables, you can't get much more elegant than using Substring:

var pr = id.Substring(0, 2);
var pa = id.Substring(2, 2);
var fo = id.Substring(4, 2);
var it = id.Substring(6);

Were you looking for an array of four 2-character substrings, you could get fancier:

var parts = new string[4];
for (int i = 0 ; i != parts.Length ; i ++) {
    parts[i] = id.Substring(2*i, 2);
}

EDIT: The same can be done with a LINQ expression:

var parts = Enumerable
    .Range(0, id.Length/2)
    .Select(i => x.Substring(2*i, 2))
    .ToArray();

Answer 3

Try regular expression.

 var id = "01020304";
 string pat = "(?:(\\d{2}))";

 var result = Regex.Split(id, pat).Where(p=>p!=string.Empty);
 foreach (var t in result)
 {
   Console.WriteLine(t);
 }

Answer 4

If you are always going to have an input of 8 characters and always require 4 variables, you can simply split the string with the Substring(...) method:

var id = "01020304";
string pr = id.Substring(0, 2);
string pa = id.Substring(2, 2);
string fo = id.Substring(4, 2);
string it = id.Substring(6, 2);

Otherwise, you can employ a method of running through a for loop and splitting off two characters at a time.

Answer 5

Here is a solution with a loop, which would support strings of this format, any length:

string id  = "01020304";
int length = id.Length;

int[] holder = new int[length/2];

for (int i = 0; i < length/2; i++) {
    holder[i] = id.Substring(i*2, 2);
}

Answer 6

Here is a version using Linq.

Interestingly enough, this is not so easy to achieve with just the built-in operators. The version below just uses the Linq extension methods that come with the .NET framework:

var result = "01020304".ToCharArray().
           Select((c,i) => new { idx = i % 2 == 1 ? i - 1 : i, ch = c }).
           GroupBy(e => e.idx, 
              (k,g) => new String(g.Select(e => e.ch).ToArray()));

If you use the morelinq Extensions the query can be simplified to

 var result = "01020304".ToCharArray().
                     Batch(2).Select(ca => new String(ca.ToArray()));