Copy Method (IntPtr, Char[], Int32, Int32)

Marshal.Copy Method (IntPtr, Char[], Int32, Int32)


Copies data from an unmanaged memory pointer to a managed character array.

Namespace:   System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)

public static void Copy(
	IntPtr source,
	char[] destination,
	int startIndex,
	int length


Type: System.IntPtr

The memory pointer to copy from.

Type: System.Char[]

The array to copy to.

Type: System.Int32

The zero-based index in the destination array where copying should start.

Type: System.Int32

The number of array elements to copy.

Exception Condition

source, destination, startIndex, or length is null.

Unmanaged, C-style arrays do not contain bounds information, which prevents the startIndex and length parameters from being validated. Thus, the unmanaged data corresponding to the source parameter populates the managed array regardless of its usefulness. You must initialize the managed array with the appropriate size before calling this method.

The following example copies an array to unmanaged memory and then copies the unmanaged array back to managed memory.

// Remember that the actual size of System.Char in unmanaged memory is 2.
using System;
using System.Runtime.InteropServices;

class Example

    static void Main()
        // Create a managed array.
        char[] managedArray = new char[1000];
        managedArray[0] = 'a';
        managedArray[1] = 'b';
        managedArray[2] = 'c';
        managedArray[3] = 'd';
        managedArray[999] = 'Z';

        // Initialize unmanaged memory to hold the array.
        // int size = Marshal.SizeOf(managedArray[0]) * managedArray.Length;  // Incorrect
        int size = Marshal.SystemDefaultCharSize * managedArray.Length;       // Correct

        IntPtr pnt = Marshal.AllocHGlobal(size);

            // Copy the array to unmanaged memory.
            Marshal.Copy(managedArray, 0, pnt, managedArray.Length);

            // Copy the unmanaged array back to another managed array.

            char[] managedArray2 = new char[managedArray.Length];

            Marshal.Copy(pnt, managedArray2, 0, managedArray.Length);
            Console.WriteLine("Here is the roundtripped array: {0} {1} {2} {3} {4}",
                               managedArray2[0], managedArray2[1], managedArray2[2], managedArray2[3],

            Console.WriteLine("The array was copied to unmanaged memory and back.");

            // Free the unmanaged memory.




requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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