拆分输入字符串并形成逗号分隔的输出

Question

We have an input string with several dots separated values and each of these units is separated by space. If the input is like:

string input = "1.2 3.4 5.6 7.8 9", we need to break it as:

string beforeDots="1,3,5,7,9" // all ints before the dot.

string afterDots="2,4,6,8" // all ints after the dot.

We have tried this by:

string inputSplit=input.Split(' ');
string beforeDots=string.Empty;
string afterDots=string.Empty;
foreach (string input in inputSplit)
{
   if (input.IndexOf(".") > 0)
      afterDots += "," + s.Split('.')[1];
   else
      beforeDots += "," + s;
}

if(afterDots.Length > 0)
   afterDots = afterDots.Substring(1, afterDots.Length - 1);

if(beforeDots.Length > 0)
   beforeDots = beforeDots.Substring(1, beforeDots.Length - 1);

Is there any better way to solve this either by linq or by some easier logic?

Answer 1

You could clean your logic up a little bit:

string input = "1.2 3.4 5.6 7.8 9";

List<string> beforeDot = new List<string>();
List<string> afterDot = new List<string>();

foreach(string s in input.Split())
{
    var split = s.Split('.');

    beforeDot.Add(split[0]);

    if(split.Length == 2)
    {               
        afterDot.Add(split[1]);
    }
}

string beforeDots = string.Join(", ", beforeDot);
string afterDots = string.Join(", ", afterDot);

This gives you the added benefit of having the numbers preserved individually (beforeDot, afterDot) if you need to use it for other logic.

There really isn't any need to use LINQ here.

Fiddle here

Answer 2

I suggest splitting the string, and then using linq.

Edit: I missed the space between number before, the updated method below will work with the spaces taken into account.

string input = "1.2 3.4 5.6 7.8 9";
//split, assign index, flatten, group by index.
var inputGroups = input.Split(' ').Select(x => x.Split('.')).Select(x=>x.Select((number, i)=>new { Number = number, Index = i })).SelectMany(x=>x).GroupBy(x=>x.Index);
//group with index 0 was before the dot
var beforeDot= inputGroups.Where(grp=>grp.Key == 0) .FirstOrDefault().Select(x=>x.Number);
//group with key 1 was after the dot
var afterDot= inputGroups.Where(x=>x.Key == 1).FirstOrDefault().Select(x => x.Number);

//then use string.Join(",", str);
var commaSeparatedBefore = string.Join(",",beforeDot);
var commaSeparatedAfter = string.Join(",", afterDot);

Answer 3

You can generalize this for any T with extremely simple and mantainable code without using linq:

public static (IEnumerable<T> Prefixes, IEnumerable<T> suffixes)
    Separate<T>(this IEnumerable<T> source, T splitOn, T resetOn)
{
    if (source == null)
        throw new ArgumentNullException(nameof(source));

    var isSuffix = false;
    var prefixes = new List<T>();
    var suffixes = new List<T>();

    foreach (var c in source)
    {
        if (c.Equals(splitOn))
        {
            isSuffix = true;
        }
        else if (c.Equals(resetOn))
        {
            isSuffix = false;
        }
        else
        {
            if (isSuffix)
            {
                suffixes.Add(c);
            }
            else
            {
                prefixes.Add(c);
            }
        }
    }

    return (prefixes, suffixes);
}

And usage is rather straightforward:

var res = "1.2 3.4 5.6 7.8 9".Separate('.', ' ');

Answer 4

The output is strings (which can be parsed after the fact):

class Program
{
    static void Main(string[] args)
    {
        var input = "1.2 3.4 5.6 7.8 9";

        var pairs = input.Split(' ').Select(
            s =>
            {
                var split = s.Split('.');

                return new KeyValuePair<string,string>(split[0],split.Length > 1 ? split[1] : null);
            });

        Console.WriteLine(String.Join(",", pairs.Select(p => p.Key)));
        Console.WriteLine(String.Join(",", pairs.Where(p=>p.Value != null).Select(p => p.Value)));

        Console.ReadKey();
    }
}

Answer 5

You, guys, are overcomplicating this. All in all, these are just decimal numbers. So I'll do this:

static void Main(string[] args)
{
    var input = "1.2 3.4 5.6 7.8 9";
    var numbers = input.Split().Select(s => decimal.Parse(s));

    var beforeDots = numbers.Select(n => (int)Math.Truncate(n));
    var afterDots = numbers.Select(n => (int)((n - Math.Truncate(n)) * 10));

    Console.WriteLine(string.Join(",", beforeDots));
    Console.WriteLine(string.Join(",", afterDots));

    Console.ReadLine();
}

// Output:
// 1,3,5,7,9
// 2,4,6,8,0

Answer 6

You can do this:

var tmp = input.Split(' ').Select(x => x.Split('.'));
var beforeDots = string.Join(",", tmp.Select(x => x.First()));
var afterDots = string.Join(",", tmp.Select(x => x.ElementAtOrDefault(1)).Where(x => x != null));