I am trying to convert an object (is declared here as 'obj': object is array, primitive) to a string array.
object can be anything uint[], int16[], etc.
I have been trying to use
string[] str = Array.ConvertAll<object, string>((object[])obj, Convert.ToString);The problem occurs when I try to cast the unknown type object into object[]. I have been getting casting error.
One attempt I made, which failed, was using
object[] arr = (object[])obj;or
IEnumerable<object> list = obj as IEnumerable<object>
object[] arr = (object[])list;I saw postings regarding value type and reference type issue on casting.
Would there be a simple code that can handle casting to object[] regardless of type of object, as long as it is an array ? I am trying to avoid manual handling of every possible type casting.
13 Answers
You can use the fact that every array implements IEnumerable:
string[] arr = ((IEnumerable)obj).Cast<object>() .Select(x => x.ToString()) .ToArray();This will box primitives appropriately, before converting them to strings.
The reason the cast fails is that although arrays of reference types are covariant, arrays of value types are not:
object[] x = new string[10]; // Fine
object[] y = new int[10]; // FailsCasting to just IEnumerable will work though. Heck, you could cast to Array if you wanted.
If it's always a collection of some type (array, list, etc ...) then try casting back to plain old System.Collections.IEnumerable and go from there
string[] str = ((System.Collections.IEnumerable)obj) .Cast<object>() .Select(x => x.ToString()) .ToArray();Here is a more thorough implementation that handles non-collections as well
static string[] ToStringArray(object arg) { var collection = arg as System.Collections.IEnumerable; if (collection != null) { return collection .Cast<object>() .Select(x => x.ToString()) .ToArray(); } if (arg == null) { return new string[] { }; } return new string[] { arg.ToString() };
}my example:
public class TestObject { public string Property1 { get; set; } public string Property2 { get; set; } public string Property3 { get; set; } } static void Main(string[] args) { List<TestObject> testObjectList = new List<TestObject> { new TestObject() { Property1 = "1", Property2 = "2", Property3 = "3" }, new TestObject() { Property1 = "1", Property2 = "2", Property3 = "3" }, new TestObject() { Property1 = "1", Property2 = "2", Property3 = "3" } }; List<string[]> convertedTestObjectList = testObjectList.Select(x => new string[] { x.Property1, x.Property2, x.Property3 }).ToList(); }
