How to Convert string[] to eg int32[]

bonehead

Hi,

Getting invalid cast exception, when casting from string to int32[]. What's the correct approach to casting below.

Thanks.

int[] ii = ReadField("Col5", "Game", "Who");

static T ReadField(string searchCol, U searchFor, string colName)
{

Type u = typeof(T);

string[] foundValues = "4,9".Split(',');

Array a = Array.CreateInstance(u, foundValues.Lenght);

for (int i =0; i < foundValues.Lenght, i++)
a.SetValue(Convert.ChangeType(foundValues[i], u), i); <== Incorrect cast string to int32[]

return ?? (T)Convert.ChangeType(a, u);

}

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes13y ago
Accepted answer
I think the type parameter of the ReadField method needs to be T but the return type T[].

So, try it like this:

using System;

class Test
{
static void Main()
{

int[] ii = ReadField("Col5", "Game", "Who");
foreach(int i in ii) Console.Write("{0} ",i); // 4 9
Console.ReadKey();
}

static T[] ReadField(string searchCol, U searchFor, string colName)
{

Type u = typeof(T);
string[] foundValues = "4,9".Split(',');
Array a = Array.CreateInstance(u, foundValues.Length);

for (int i =0; i < foundValues.Length; i++)
a.SetValue(Convert.ChangeType(foundValues[i], u), i);

return (T[])a;
}
}
bonehead13y ago
I agree
Vulpes13y ago
I think myself that you'll need to have two methods - one for converting to a scalar T and the other for converting to an array of T. I just don't see how you can accomodate both cases in a single method.

As you say, you can't overload the method on return type so you'll have to use different names.
bonehead13y ago
Hi Vulpes, Sorry for the confusion, only showing code for issue with casting to int16[], I have no issue if T is of type int, double, or string: return (T)Convert.ChangeType(foundValue, u);
bonehead13y ago
Hi Vulpes, Since overloaded methods cannot differ by return type, I think the return type has to be T where T can be an int, double, int[] etc ??