Marshal.WriteInt32 Method (IntPtr, Int32)

 
System_CAPS_noteNote

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Writes a 32-bit signed integer value to unmanaged memory.

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

[SecurityCriticalAttribute]
public static void WriteInt32(
	IntPtr ptr,
	int val
)

Parameters

ptr
Type: System.IntPtr

The address in unmanaged memory to write to.

val
Type: System.Int32

The value to write.

Exception Condition
AccessViolationException

ptr is not a recognized format.

-or-

ptr is null.

-or-

ptr is invalid.

WriteInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before setting its element values.

Writing to unaligned memory locations is supported.

The following example demonstrates how to read and write to an unmanaged array using the ReadInt32 and WriteInt32 methods.

static void ReadWriteInt32()
{
    // Allocate unmanaged memory. 
    int elementSize = 4;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt32(unmanagedArray, i * elementSize, ((Int32)(i + 1)));
    }
    Console.WriteLine("Unmanaged memory written.");

    Console.WriteLine("Reading unmanaged memory:");
    // Print the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Console.WriteLine(Marshal.ReadInt32(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

    Console.WriteLine("Done. Press Enter to continue.");
    Console.ReadLine();
}

SecurityCriticalAttribute

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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