How to convert object[] to List<string> in one line of C# 3.0?

Question

ok I give up, how do you do this in one line?

public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    //List<string> fields = values.ToList<string>();
    //List<string> fields = values as List<string>;
    //List<string> fields = (List<string>)values;

    List<string> fields = new List<string>();
    foreach (object value in values)
    {
        fields.Add(value.ToString());
    }

    //process the fields here knowning they are strings
    ...
}

Solution 1

Are you using C# 3.0 with LINQ? It's pretty easy then:

List<string> fields = values.Select(i => i.ToString()).ToList();

Solution 2

If you have LINQ available (in .NET 3.5) and C# 3.0 (for extension methods), then there is quite a nice one liner:

var list = values.Cast<string>().ToList();

You're not going get anything much shorter that what you've posted for .NET 2.0/C# 2.0.

Caveat: I just realised that your object[] isn't necessarily of type string. If that is in fact the case, go with Matt Hamilton's method, which does the job well. If the element of your array are in fact of type string, then my method will of course work.

Solution 3

C# 2.0:

List<string> stringList = new List<string>(Array.ConvertAll<object,string>(values, new Converter<object,string>(Convert.ToString)));

Solution 4

One more variant that might be correct:

List<string> list = values.OfType<string>().ToList();

This will filter out any objects in the original list that are not string objects, instead of either throwing an exception or trying to convert them all into strings.

Solution 5

Array.ConvertAll(inputArray, p => p.ToString())

This converts an array of object type to array of string. You can convert to other type array by changing the lambda expression.

View more solutions

Comments

[Lucas]

Technically it's C# 3.0, which can be used to target .NET frameworks 2.0, 3.0, or 3.5 in VS2008. Confusing, I know :)

[Scott Ivey]

great answer - much simpler than a linq select.

[Mauricio Scheffer]

Note that this will fail if any value is not a string.

[Noldorin]

@Andrew: Yeah, good point. I clearly read the question too quickly. Caveat mentioned in my post now.

[Angry Dan]

.Cast is very terse, thanks, nice to know, but in this case my objects as you noted in your caveat, are coming from a XAML Multibinding and could theoretically be any object and hence this would break if I sent a non-string

[Angry Dan]

as you correctly assumed from the context, the objects are coming from XAML and theoretically could be of any type, so with this answer when I send an integer, it gets correctly converted to a string, perfect

[Noldorin]

@Edward Tanguay: Yeah, it now makes sense why you were doing that loop. No problem...

[Jim Schubert]

This is technically a two-liner if you count the using directive :D