Interlocked.Add Method

Definition

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

Overloads

Add(Int32, Int32)

Adds two 32-bit integers and replaces the first integer with the sum, as an atomic operation.

Add(Int64, Int64)

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

Add(Int32, Int32)

Adds two 32-bit integers and replaces the first integer with the sum, as an atomic operation.

public static int Add (ref int location1, int value);
Parameters
location1
Int32

A variable containing the first value to be added. The sum of the two values is stored in location1.

value
Int32

The value to be added to the integer at location1.

Returns

The new value stored at location1.

Exceptions

The address of location1 is a null pointer.

Remarks

This method handles an overflow condition by wrapping: if the value at location1 is Int32.MaxValue and value is 1, the result is Int32.MinValue; if value is 2, the result is (Int32.MinValue + 1); and so on. No exception is thrown.

Add(Int64, Int64)

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

public static long Add (ref long location1, long value);
Parameters
location1
Int64

A variable containing the first value to be added. The sum of the two values is stored in location1.

value
Int64

The value to be added to the integer at location1.

Returns

The new value stored at location1.

Exceptions

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 Read method and 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.

See Also

Applies to