atomic_compare_exchange_weak, atomic_compare_exchange_strong, atomic_compare_exchange_weak_explicit, atomic_compare_exchange_strong_explicit
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| 在头文件 <stdatomic.h> 中定义
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| _Bool atomic_compare_exchange_strong( volatile A* obj, C* expected, C desired ); |
(1) | |
| _Bool atomic_compare_exchange_weak( volatile A *obj, C* expected, C desired ); |
(2) | |
| _Bool atomic_compare_exchange_strong_explicit( volatile A* obj, C* expected, C desired, |
(3) | |
| _Bool atomic_compare_exchange_weak_explicit( volatile A *obj, C* expected, C desired, |
(4) | |
原子的值进行比较，指出，
obj指出，expected的价值，如果这些都是平等的，取代了以前的desired（执行读 - 修改 - 写操作）。否则，加载的实际值所指向的obj到*expected（执行负载操作）.原文：
Atomically compares the value pointed to by
obj with the value pointed to by expected, and if those are equal, replaces the former with desired (performs read-modify-write operation). Otherwise, loads the actual value pointed to by obj into *expected (performs load operation).内存模型的读 - 修改 - 写和加载操作
succ和fail。 （1-2）版本默认情况下，使用memory_order_seq_cst.原文：
The memory models for the read-modify-write and load operations are
succ and fail respectively. The (1-2) versions use memory_order_seq_cst by default.的弱形式（（1）和（3））的功能允许意外失败，即，如果*obj != *expected作为即使它们是相等的。当比较和交换是在一个循环中，弱版本会带来更好的性能，在某些平台上。当一个弱的比较和交换，需要一个循环，一个强大的，强大的一个是最好的.
原文：
The weak forms ((1) and (3)) of the functions are allowed to fail spuriously, that is, act as if *obj != *expected even if they are equal. When a compare-and-exchange is in a loop, the weak version will yield better performance on some platforms. When a weak compare-and-exchange would require a loop and a strong one would not, the strong one is preferable.
这是一个通用函数定义的所有原子的对象类型。
A是一个原子对象的类型，C非原子的类型，对应于A.原文：
This is a 通用函数 defined for all atomic object types.
A is the type of an atomic object, C is the non-atomic type corresponding to A.[编辑] 参数
| obj | - | 指针的原子对象测试和修改
原文： pointer to the atomic object to test and modify |
| expected | - | 预期发现的原子对象中的值的指针
原文： pointer to the value expected to be found in the atomic object |
| desired | - | 要存储的值的原子对象中，如果是如预期的那样
原文： the value to store in the atomic object if it is as expected |
| succ | - | 内存同步的读 - 修改 - 写操作的顺序，如果比较成功。允许所有的值都.
原文： the memory synchronization ordering for the read-modify-write operation if the comparison succeeds. All values are permitted. |
| fail | - | 存储器同步的负载操作的顺序，如果比较失败。不能是memory_order_release或memory_order_ack_rel并且不能指定更强的顺序比
succ原文： the memory synchronization ordering for the load operation if the comparison fails. Cannot be memory_order_release or memory_order_ack_rel and cannot specify stronger ordering than succ |
[编辑] 返回值
的比较结果：true如果
*obj等于*exp，false否则.原文：
The result of the comparison: true if
*obj was equal to *exp, false otherwise.[编辑] 另请参阅
| 交换值与原子的对象的值 原文： swaps a value with the value of an atomic object （函数） | |
| C++ documentation for atomic_compare_exchange_weak, atomic_compare_exchange_strong, atomic_compare_exchange_weak_explicit, atomic_compare_exchange_strong_explicit
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