Split out ints from string

Question

Let\'s say I have a web page that currently accepts a single ID value via a url parameter:
http://example.com/mypage.aspx?ID=1234

I want to change it to acce

Answer 1

List<int> convertIDs = new List<int>;
string[] splitIds = ids.split(',');
foreach(string s in splitIds)
{
    convertIDs.Add(int.Parse(s));
}

For completeness you will want to put try/catches around the for loop (or around the int.Parse() call) and handle the error based on your requirements. You can also do a tryparse() like so:

List<int> convertIDs = new List<int>;
string[] splitIds = ids.split(',');
foreach(string s in splitIds)
{
    int i;
    int.TryParse(out i);
    if (i != 0)
       convertIDs.Add(i);
}

Answer 2

Final code snippet that takes what I hope is the best from all the suggestions:

Function GetIDs(ByVal IDList As String) As List(Of Integer)
    Dim SplitIDs() As String = IDList.Split(new Char() {","c}, StringSplitOptions.RemoveEmptyEntries)
    GetIDs = new List(Of Integer)(SplitIDs.Length)
    Dim CurID As Integer
    For Each id As String In SplitIDs
        If Integer.TryParse(id, CurID) Then GetIDs.Add(CurID)
    Next id
End Function

I was hoping to be able to do it in one or two lines of code inline. One line to create the string array and hopefully find something in the framework I didn't already know to handle importing it to a List<int> that could handle the cast intelligently. But if I must move it to a method then I will. And yes, I'm using VB. I just prefer C# for asking questions because they'll get a larger audience and I'm just about as fluent.

Answer 3

You can instantiate a List<T> from an array.

VB.NET:

Dim lstIDs as new List(of Integer)(ids.split(','))

This is prone to casting errors though if the array contains non-int elements

Answer 4

To continue on previous answer, quite simply iterating through the array returned by Split and converting to a new array of ints. This sample below in C#:

        string[] splitIds = stringIds.Split(',');

        int[] ids = new int[splitIds.Length];
        for (int i = 0; i < ids.Length; i++) {
            ids[i] = Int32.Parse(splitIds[i]);
        }

Answer 5

split is the first thing that comes to mind, but that returns an array, not a List; you could try something like:

List<int> intList = new List<int>;

foreach (string tempString in ids.split(',')
{
    intList.add (convert.int32(tempString));
}

Answer 6

You can use string.Split() to split the values once you have extracted them from the URL.

string[] splitIds = ids.split(',');