CODEWITHSUNDEEP
c#.net.net-4.0
Suraj
Suraj

Reputation: 36557

Attempt to convert object[] to ValueType[] at runtime

Is it possible to convert an object[] to a value type such as double[] when the value type is only known at runtime? An exception is perfectly acceptable if an object in object[] cannot be converted to the value element type (say double) using the .net built-in conversions.

var original = new object[] { 1 , 2 , 3 , 4 , 5 , 6 }
Type resultType = typeof( double[] ); // or any means of getting a type at runtime
var result = ??

The following attempts have failed:

# error: Object must impliment IConvertible
Convert.ChangeType( original , resultType );

# error: Object cannot be stored in an array of this type.
var result = Array.CreateInstance( resultType , original.Length );
for ( int i = 0 ; i < original.Length ; i++ )
{
    result.SetValue( Convert.ChangeType( original[ i ] , resultType.GetElementType() ) , i );
}

Upvotes: 2

Views: 1124

Answers (2)

YoryeNathan
YoryeNathan

Reputation: 14522

private T[] Cast<T>(params object[] items)
{
    if (!typeof(T).IsValueType)
    {
        throw new ArgumentException("Destined type must be Value Type");
    }

    return items.Cast<T>().ToArray();
}

Upvotes: 0

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726699

Your last attempt was very close: the first line should be

var result = Array.CreateInstance(resultType.GetElementType(), original.Length);

because Array.CreateInstance takes element type as its first parameter. Other than that, it should work perfectly.

Upvotes: 4

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