CODEWITHSUNDEEP
c#
walruz
walruz

Reputation: 1319

Determine array size after GetType()

Here is what I have

        int[] x = new int[10];

        Type type = x.GetType();
        if (type.IsArray)
        {
            Type typeOfElement = type.GetElementType();
            int length = 0; // how do I get array's length????
        }

Is there a way to determine length of array using Type?

Upvotes: 3

Views: 1584

Answers (4)

Jeppe Stig Nielsen
Jeppe Stig Nielsen

Reputation: 61912

Arrays of different lengths will have identical types, for example new int[10] and new int[11] have identical (run-time) types.

This means you cannot reconstruct the length from the System.Type alone; you need the reference to the actual array instance.

Upvotes: 0

Geka P
Geka P

Reputation: 607

Using reflection, you cannot get length of array. You can access properties of the object, know their types and methods provided by that object(class). But you cannot recreate or know what was the lengths of an array by knowing just its type.

Upvotes: 0

Amir Popovich
Amir Popovich

Reputation: 29836

Use Array.Length:

int[] x = new int[10];

Type type = x.GetType();
if (type.IsArray)
{
    int length = (x as Array).Length;
}

Edit: Just realized that you asked about getting the length from the type and not from the instance. You can't do that since your type will always be an array and it doesn't matter what sizes they have:

int[] arr1 = new int[10];
int[] arr2 = new int[11];

bool areEqual = arr1.GetType() == arr2.GetType(); // true

Upvotes: 2

Patrick Hofman
Patrick Hofman

Reputation: 156928

There is no information on the type regarding the size of the array. It is just an array, nothing more.

So the only way to get the size is going back to the instance. There, and only there, you can find the size of the array.

You could do that by querying the Length property using reflection.

Upvotes: 1

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