Atomically replaces the current value of the referenced object with the result of arithmetic subtraction of the value andarg. This operation is a read-modify-write operation. Memory is affected according to the value oforder.

• For signed integral types, arithmetic is defined to use two’s complement representation. There are no undefined results.
• For floating-point types, thefloating-point environment in effect may be different from the calling thread's floating-point environment. The operation need not be conform to the correspondingstd::numeric_limits traits but is encouraged to do so. If the result is not a representable value for its type, the result is unspecified but the operation otherwise has no undefined behavior.
• For pointer types, the result may be an undefined address, but the operation otherwise has no undefined behavior.
  • Ifstd::remove_pointer_t<T> is not a complete object type, the program is ill-formed.

This overload participates in overload resolution only ifstd::is_const_v<T> isfalse.

[edit]Parameters

[edit]Return value

The value referenced by*ptr, immediately preceding the effects of this function.

[edit]Example

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

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