function
<future>

std::future_category

const error_category& future_category() noexcept;
Return future category
Returns a reference to the static object of the error_category type that has the following characteristics:

error_condition objects describing errors that correspond to the enum type future_errc are associated to this category. What constitutes one of these correspondences depends on the operating system and the particular library implementation.

Parameters

none

Return value

A reference to the future error_category object.

Example

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// std::future_category example:
#include <iostream> // std::cerr
#include <future> // std::promise, std::future_error, std::future_category
int main ()
{
 std::promise<int> prom;
 try {
 prom.get_future();
 prom.get_future(); // throws a std::future_error of the future category
 }
 catch (std::future_error& e) {
 if (e.code().category() == std::future_category())
 std::cerr << "future_error of the future category thrown\n";
 }
 return 0;
}

Output (on stderr ):

future_error of the future category thrown


Exception safety

No-throw guarantee: this function never throws exceptions.

See also

future_errc
Error conditions for future objects (enum class)

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