IntPtr.Subtraction Operator (IntPtr, Int32)

.NET Framework (current version)
 
System_CAPS_noteNote

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equivalentCodeEntityM:System.IntPtr.Subtract(System.IntPtr,System.Int32)

Subtracts an offset from the value of a pointer.

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

public static IntPtr operator -(
	IntPtr pointer,
	int offset
)

Parameters

pointer
Type: System.IntPtr

The pointer to subtract the offset from.

offset
Type: System.Int32

The offset to subtract.

Return Value

Type: System.IntPtr

A new pointer that reflects the subtraction of offset from pointer.

The Subtraction method defines the subtraction operation for IntPtr objects. It enables code such as the following.

int[] arr = { 2, 4, 6, 8, 10, 12, 14, 16, 18, 20};
unsafe {            
   fixed(int* parr = &arr[arr.GetUpperBound(0)])
   {
      IntPtr ptr = new IntPtr(parr);
      for (int ctr = 0; ctr <= arr.GetUpperBound(0); ctr++)
      {
         IntPtr newPtr = ptr - ctr * sizeof(Int32);
         Console.Write("{0}   ", Marshal.ReadInt32(newPtr));
      }
   }
}   
// The example displays the following output:
//       20   18   16   14   12   10   8   6   4   2      

Languages that do not support custom operators can call the Subtract method instead.

The subtraction operation does not throw an exception if the result is too small to represent as a pointer on the specified platform. Instead, it is performed in an unchecked context.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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