operator""h is the chrono user-defined literal that turns a numeric h-suffixed literal into an hours duration. Thus, 23h provides a readable alternative to hours{23}. section 4.2.3
Readable duration syntax
When 23h is encountered, operator""h is called with the numeric value and returns hours(23). Make chrono literals visible through std::chrono, std::literals, or std::chrono_literals. section 4.2.3
hours operator""h(long long _Val) {
return hours(_Val);
}
A simplified implementation shows the literal operator accepting a long long value and returning the stronger hours type. section 4.2.3
