[time.clock.file.overview]

# 30 Time library [[time]](./#time)

## 30.7 Clocks [[time.clock]](time.clock#file.overview)

### 30.7.6 Type file_clock [[time.clock.file]](time.clock.file#overview)

#### 30.7.6.1 Overview [time.clock.file.overview]

namespace std::chrono {using file_clock = *see below*;}

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/time.tex#L3369)

file_clock is an alias for a type
meeting the [*Cpp17TrivialClock*](time.clock.req#:Cpp17TrivialClock "30.3 Cpp17Clock requirements [time.clock.req]") requirements ([[time.clock.req]](time.clock.req "30.3 Cpp17Clock requirements")), and
using a signed arithmetic type for file_clock​::​rep[.](#1.sentence-1)

file_clock is used to create the time_point system
used for file_time_type ([[filesystems]](filesystems "31.12 File systems"))[.](#1.sentence-2)

Its epoch is unspecified, andnoexcept(file_clock​::​now()) is true[.](#1.sentence-3)

[*Note [1](#note-1)*:

The type that file_clock denotes can be
in a different namespace than std​::​chrono,
such as std​::​filesystem[.](#1.sentence-4)

â *end note*]
