转换逗号分隔的列表 <string> 列出 <Int>

Question

I have a List<string> containing comma separated values, for example, each item looks like "123, 123, 123". Now, I want to convert this to a List<int> . How can I do that?

I have tried the following:

List<int> TagIds = parameters.AccidentId.Split(',').Select(int.Parse).ToList();

But It says that:

System.Collections.Generic.List does not contain a definition of "Split" accepting a first argument of type 'System.Collections.Generic.List' could be found.

I define my AccidentId like this:

if (AccidentId != null && AccidentId.itemsSelected != null)
{
    parameters.AccidentId = new List<string>();
    foreach(var param in AccidentId.itemsSelected)
    {
        parameters.AccidentId.Add(param);
    }
}  

Answer 1

You effectively have a list of lists. Each string in your list is a comma separated list.

You can use SelectMany to flatten multiple sequences into a single list.

Something like:

parameters.AccidentId.SelectMany(s => s.Split(',').Select(int.Parse)).ToList()

This is roughly equivalent to

List<int> TagIds = new List<int>();

foreach(string s in parameters.AccidentId)
{
    string[] accidentIds = s.Split(',');
    foreach(string accidentId in accidentIds)
    {
        TagIds.Add(int.Parse(accidentId));
    }
} 

Answer 2

If parameters.AccidentId is a List<string> and not a single string you can't use String.Split directly. But then you should rename the property anyway, fe AccidentIdList .

You could use this approach:

List<int> TagIds = parameters.AccidentId
    .SelectMany(id => id.Split(',').Select(int.Parse))
    .ToList();

or with Array.ConvertAll :

List<int> TagIds = parameters.AccidentId
    .SelectMany(id => Array.ConvertAll(id.Split(','), int.Parse))
    .ToList();