c# byte[] 转换为 IntPtr几种方法



有几种方法可以访问与字节数组相对应的 IntPtr。

第一种，使用不安全的代码块来访问直接指向字节数组的指针。

代码如下 复制代码

unsafe
{
byte[] test = newbyte[5];
fixed (byte* p = &test[0])
{
*p = 0xff;
}
}

第二种，可以使用 GCHandle 来获得对象。

代码如下 复制代码

using System.Runtime.InteropServices;

byte[] test = new byte[5];
GCHandle hObject = GCHandle.Alloc(test, GCHandleType.Pinned);
IntPtr pObject = hObject.AddrOfPinnedObject();

if(hObject.IsAllocated)
hObject.Free();

第三种， 通过 LocalAlloc 创建内存块并将数据封送处理到该内存块。

 

 

代码如下 复制代码

[DllImport(coredll.dll,SetLastError=true)]
public static extern IntPtr LocalAlloc(uint uFlags, uint uBytes);
[DllImport(coredll.dll,SetLastError=true)]
public static extern IntPtr LocalFree(IntPtr hMem);
[DllImport(coredll.dll,SetLastError=true)]
public static extern IntPtr LocalReAlloc(IntPtr hMem, uint uBytes, uint fuFlags);

public const uint LMEM_FIXED = 0;
public const uint LMEM_MOVEABLE = 2;
public const uint LMEM_ZEROINIT = 0x0040;

byte[] test = new byte[5];
IntPtr p = LocalAlloc(LMEM_FIXED | LMEM_ZEROINIT, (uint)test.Length);

if (p == IntPtr.Zero)
{
throw new OutOfMemoryException();
}
else
{
Marshal.Copy(test, 0, p, test.Length);
}

using System;
using System.Runtime.InteropServices;

class Example
{

    static void Main()
    {
        // Create a managed array.
        byte[] managedArray = { 1, 2, 3, 4 };

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

        IntPtr pnt = Marshal.AllocHGlobal(size);

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

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

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

            Marshal.Copy(pnt, managedArray2, 0, managedArray.Length);

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

        }
        finally
        {
            // Free the unmanaged memory.
            Marshal.FreeHGlobal(pnt);
        }



    }

}