• Article

Interlocked.Add Method (Int64%, Int64)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Adds two 64-bit integers and replaces the first integer with the sum, as an atomic operation.

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

Syntax

'Declaration
Public Shared Function Add ( _
    ByRef location1 As Long, _
    value As Long _
) As Long

public static long Add(
    ref long location1,
    long value
)

Parameters

  • location1
    Type: System.Int64%
    A variable that contains the first value to be added. The sum of the two values is stored in location1.
  • value
    Type: System.Int64
    The value to be added to the integer at location1.

Return Value

Type: System.Int64
The new value stored at location1.

Exceptions

Exception Condition
NullReferenceException

The address of location1 is a null pointer.

Remarks

This method handles an overflow condition by wrapping: If the value at location1 is Int64.MaxValue and value is 1, the result is Int64.MinValue; if value is 2, the result is (Int64.MinValue + 1); and so on. No exception is thrown.

The 64-bit overloads of the Increment, Decrement, and Add methods are truly atomic only on systems where a System.IntPtr is 64 bits long. On other systems, these methods are atomic with respect to each other, but not with respect to other means of accessing the data. Thus, to be thread safe on 32-bit systems, any access to a 64-bit value must be made through the members of the Interlocked class.

Version Notes

Silverlight for Windows Phone Silverlight for Windows Phone

 64-bit members of the Interlocked class are present but not supported.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.