I'm trying to do an exercise which uses atomic operations. I want to do a comparison between a position of atomic array and an atomic int using compare_exchange.
My code is:
我正在尝试进行使用原子操作的练习。我想使用compare_exchange对原子数组的位置和原子int进行比较。我的代码是：
std::array<std::atomic<long int>, 20> xx;
std::atomic<long int> number;
I want to do:
我想要做：
if (xx[i] > number)
number = xx[i];
How can use compare_exchange_weak() in my case? I saw a lot of times http://en.cppreference.com/w/cpp/atomic/atomic but I don't understand it.
在我的情况下如何使用compare_exchange_weak（）？我看过很多次http://en.cppreference.com/w/cpp/atomic/atomic但我不明白。
1 个解决方案
#1
2
You can't. std::atomic allows various atomic operations on a single object. To perform an atomic operation involving more than one object, you'll need a lock.
你不能。 std :: atomic允许对单个对象进行各种原子操作。要执行涉及多个对象的原子操作，您需要锁定。
compare_exchange, as your link describes, atomically compares the object for equality with a non-atomic value, and updates it depending on that comparison. It doesn't compare two atomic values.
compare_exchange，正如您的链接所描述的那样，原子地将对象与非原子值进行相等性比较，并根据该比较对其进行更新。它不比较两个原子值。
#1
2
You can't. std::atomic allows various atomic operations on a single object. To perform an atomic operation involving more than one object, you'll need a lock.
你不能。 std :: atomic允许对单个对象进行各种原子操作。要执行涉及多个对象的原子操作，您需要锁定。
compare_exchange, as your link describes, atomically compares the object for equality with a non-atomic value, and updates it depending on that comparison. It doesn't compare two atomic values.
compare_exchange，正如您的链接所描述的那样，原子地将对象与非原子值进行相等性比较，并根据该比较对其进行更新。它不比较两个原子值。