table of contents
std::chrono::is_am,std::chrono::is_pm,std::chrono::make12,std::chrono::make24(3) | C++ Standard Libary | std::chrono::is_am,std::chrono::is_pm,std::chrono::make12,std::chrono::make24(3) |
NAME¶
std::chrono::is_am,std::chrono::is_pm,std::chrono::make12,std::chrono::make24 - std::chrono::is_am,std::chrono::is_pm,std::chrono::make12,std::chrono::make24
Synopsis¶
Defined in header <chrono>
constexpr bool is_am( const std::chrono::hours& h ) noexcept; (1)
(since C++20)
constexpr bool is_pm( const std::chrono::hours& h ) noexcept; (2)
(since C++20)
constexpr std::chrono::hours make12( const std::chrono::hours& h )
(3) (since C++20)
noexcept;
constexpr std::chrono::hours make24( const std::chrono::hours& h,
(4) (since C++20)
bool is_pm ) noexcept;
These functions aid in translating between a 12-hour format time of day, and
a
24-hour format time of day.
1) Detects whether the 24-hour format time is a.m. (ante meridiem, before
midday).
2) Detects whether the 24-hour format time is p.m. (post meridiem, after
midday).
3) Returns the 12-hour equivalent of a 24-hour format time.
4) Returns the 24-hour equivalent of a 12-hour format time h, where is_pm
determines
whether the time is p.m.
Parameters¶
h - 12-hour or 24-hour format time to detect
is_pm - whether the 12-hour format time is p.m.
Return value¶
1) 0h <= h && h <= 11h.
2) 12h <= h && h <= 23h.
3) If h is in range [0h, 23h], returns the 12-hour equivalent in range [1h,
12h].
Otherwise, the return value is unspecified.
4) If h is in range [1h, 12h], returns the 24-hour equivalent in range [0h,
11h] if
is_pm is false, or in range [12h, 23h] otherwise. Otherwise, the return value
is
unspecified.
Example¶
// Run this code
#include <iostream>
#include <iomanip>
#include <utility>
#include <chrono>
int main()
{
using namespace std::chrono;
static_assert(
is_am(10h) && is_am(11h) && !is_am(12h) &&
!is_am(23h) &&
!is_pm(10h) && !is_pm(11h) && is_pm(12h) &&
is_pm(23h)
);
std::cout << "make12():\n";
for (const hours hh : { 0h, 1h, 11h, 12h, 13h, 23h }) {
const hours am{make12(hh)};
std::cout << std::setw(2) << hh.count() << "h ==
"
<< std::setw(2) << am.count() << (is_am(hh) ? "h
a.m.\n" : "h p.m.\n");
}
std::cout << "\nmake24():\n";
using p = std::pair<hours, bool>;
for (const auto& [hh, pm] : { p{1h, 0}, p{12h, 0}, p{1h, 1}, p{12h, 1} })
{
std::cout << std::setw(2) << hh.count()
<< (pm ? "h p.m." : "h a.m.")
<< " == " << std::setw(2)
<< make24(hh, pm).count() << "h\n";
}
}
Output:¶
make12():
0h == 12h a.m.
1h == 1h a.m.
11h == 11h a.m.
12h == 12h p.m.
13h == 1h p.m.
23h == 11h p.m.
make24():
1h a.m. == 1h
12h a.m. == 0h
1h p.m. == 13h
12h p.m. == 12h
2022.07.31 | http://cppreference.com |