etl/docs/chrono/duration/duration.md
2026-04-13 23:39:17 +02:00

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---
title: "duration"
---
{{< callout type="info">}}
Header: `chrono.h`
Since: `TBC`
Similar to: [std::chrono::duration](https://en.cppreference.com/w/cpp/chrono/duration.html)
Similar to: [std::chrono::duration_values](https://en.cppreference.com/w/cpp/chrono/duration_values.html)
{{< /callout >}}
Templates representing a time interval.
## duration_values
```cpp
template <typename TRep>
struct duration_values
```
```cpp
ETL_NODISCARD static ETL_CONSTEXPR TRep zero() ETL_NOEXCEPT
```
**Return**
`TRep(0)`
---
```cpp
ETL_NODISCARD static ETL_CONSTEXPR14 TRep min() ETL_NOEXCEPT
```
**Return**
`etl::numeric_limits<TRep>::min()`
---
```cpp
ETL_NODISCARD static ETL_CONSTEXPR14 TRep max() ETL_NOEXCEPT
```
**Returns**
`etl::numeric_limits<TRep>::max()`
## duration
```cpp
template <typename TRep, typename TPeriod = etl::ratio<1>>
class duration
```
```cpp
using rep = TRep
using period = typename TPeriod::type;
```
### Construction
```cpp
ETL_CONSTEXPR
duration()
ETL_NOEXCEPT
```
**Description**
Default constructor.
---
```cpp
ETL_CONSTEXPR14
duration(const etl::chrono::duration<TRep, TPeriod>& other)
ETL_NOEXCEPT
```
---
```cpp
template <typename TRep2>
ETL_CONSTEXPR14
explicit duration(const TRep2& value)
ETL_NOEXCEPT
```
---
```cpp
template <typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
duration(const etl::chrono::duration<TRep2, TPeriod2>& other)
ETL_NOEXCEPT
```
**Description**
Construct from another duration type.
Enabled if `etl::ratio_divide<TPeriod2, TPeriod>::den == 1`
### Tests
```cpp
ETL_NODISCARD
ETL_CONSTEXPR14
int compare(const time_point& other) const
ETL_NOEXCEPT
```
**Description**
Compare day with another.
if `time_point < other`, returns `-1`
else if `time_point > other`, returns `1`
else returns `0`
### Assignment
```cpp
ETL_CONSTEXPR14
etl::chrono::duration<TRep, TPeriod> operator =(const etl::chrono::duration<TRep, TPeriod>& other) ETL_NOEXCEPT
```
---
```cpp
template <typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::chrono::duration<TRep, TPeriod> operator =(const etl::chrono::duration<TRep2, TPeriod2>& other) ETL_NOEXCEPT
```
### Convertion
```cpp
ETL_CONSTEXPR14
TRep count() const
ETL_NOEXCEPT
```
**Return**
The duration count as a numeric.
---
```cpp
ETL_CONSTEXPR14
etl::common_type_t<duration> operator +() const
ETL_NOEXCEPT
```
**Description**
Implements unary plus.
---
```cpp
ETL_CONSTEXPR14
etl::common_type_t<duration> operator -() const
ETL_NOEXCEPT
```
**Description**
Implements unary minus.
---
```cpp
ETL_NODISCARD
ETL_CONSTEXPR14
etl::chrono::duration<TRep, TPeriod> absolute() const
ETL_NOEXCEPT
```
**Return**
The absolute value of the duration.
---
### Constants
```cpp
ETL_NODISCARD
static ETL_CONSTEXPR14 etl::chrono::duration<TRep, TPeriod> zero()
ETL_NOEXCEPT
```
**Return**
The duration zero value.
---
```cpp
ETL_NODISCARD
static ETL_CONSTEXPR14 etl::chrono::duration<TRep, TPeriod> min()
ETL_NOEXCEPT
```
**Return**
The minimum duration value.
---
```cpp
ETL_NODISCARD
static ETL_CONSTEXPR14 etl::chrono::duration<TRep, TPeriod> max()
ETL_NOEXCEPT
---
**Return**
The maximum duration value.
## Increment/decrement
```cpp
ETL_CONSTEXPR14
duration& operator ++()
ETL_NOEXCEPT
```
**Description**
Pre-increments the duration count.
---
```cpp
ETL_CONSTEXPR14
duration operator ++(int)
ETL_NOEXCEPT
```
**Description**
Post-increments the duration count.
---
```cpp
ETL_CONSTEXPR14
duration& operator --()
ETL_NOEXCEPT
```
**Description**
Pre-decrements the duration count.
---
```cpp
ETL_CONSTEXPR14
duration operator --(int)
ETL_NOEXCEPT
```
**Description**
Post-decrements the duration count.
### Mathematical operators
```cpp
ETL_CONSTEXPR14
duration& operator +=(const duration<TRep, TPeriod>& d)
ETL_NOEXCEPT
```
**Description**
Adds duration `d` to this duration.
---
```cpp
ETL_CONSTEXPR14
duration& operator -=(const duration<TRep, TPeriod>& d)
ETL_NOEXCEPT
```
**Description**
Subtracts duration `d` to this duration.
---
```cpp
ETL_CONSTEXPR14
duration& operator *=(const TRep& r)
ETL_NOEXCEPT
```
**Description**
Multiplies this duration by `r`.
---
```cpp
ETL_CONSTEXPR14
duration& operator /=(const TRep& r)
ETL_NOEXCEPT
```
**Description**
Divides this duration by `r`.
---
```cpp
ETL_CONSTEXPR14
duration& operator %=(const TRep& r)
ETL_NOEXCEPT
```
**Description**
Sets this duration to the modulus of `r`.
---
```cpp
ETL_CONSTEXPR14
duration& operator %=(const duration<TRep, TPeriod>& d)
ETL_NOEXCEPT
```
**Description**
Sets this duration to the modulus of duration `d`.
### Comparison
```cpp
template <typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
int compare(const duration<TRep2, TPeriod2>& other) const
ETL_NOEXCEPT
```
**Description**
Compare duration with another.
If `duration < other`, returns `-1`
else if `duration > other`, returns `1`
else returns `0`
### Non-member mathematical operators
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::common_type_t<etl::chrono::duration<TRep1, TPeriod1>,
etl::chrono::duration<TRep2, TPeriod2>>
operator +(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `+`
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::common_type_t<etl::chrono::duration<TRep1, TPeriod1>,
etl::chrono::duration<TRep2, TPeriod2> >::type
operator -(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `-`
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2>
ETL_CONSTEXPR14
etl::chrono::duration<etl::common_type_t<TRep1, TRep2>, TPeriod1>>
operator *(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const TRep2& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `*`
Enabled if `TRep2` is not a specialization of `etl::chrono::duration`.
---
```cpp
template <typename TRep1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::chrono::duration<etl::common_type_t<TRep1, TRep2>, TPeriod2>
operator *(const TRep1& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `*`
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2>
ETL_CONSTEXPR14
etl::common_type_t<TRep1, TRep2>, TPeriod1>
operator /(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const TRep2& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `/`
Enabled if `TRep2` is not a specialization of `etl::chrono::duration`.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::common_type_t<TRep1, TRep2>
operator /(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `/`
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2>
ETL_CONSTEXPR14
etl::chrono::duration<etl::common_type_t<TRep1, TRep2>, TPeriod1>
operator %(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const TRep2& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `%`
```
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
etl::common_type_t<etl::chrono::duration<TRep1, TPeriod1>,
etl::chrono::duration<TRep2, TPeriod2>>
operator %(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Operator `%`
### Non-member comparison operators
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator ==(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for equality.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator !=(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for inequality.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator <(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for less-than.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator <=(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for less-than-or-equal.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator >(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for greater-than.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
ETL_CONSTEXPR14
bool operator >=(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
ETL_NOEXCEPT
```
**Description**
Checks for greater-than-or-equal.
---
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
[[nodiscard]]
constexpr
auto operator <=>(const etl::chrono::duration<TRep1, TPeriod1>& lhs,
const etl::chrono::duration<TRep2, TPeriod2>& rhs)
noexcept
```
**Description**
Spaceship operator.
C++20
## common_type
```cpp
template <typename TRep1, typename TPeriod1, typename TRep2, typename TPeriod2>
struct common_type<etl::chrono::duration<TRep1, TPeriod1>, etl::chrono::duration<TRep2, TPeriod2>>
```
**Description**
`etl::common_type` specialisation for `etl::duration`.
## Hash
```cpp
template <typename TRep, typename TPeriod>
struct hash<etl::chrono::duration<TRep, TPeriod>>
```
## Pre-defined duration types
```cpp
etl::chrono::years
etl::chrono::months
etl::chrono::weeks
etl::chrono::days
etl::chrono::hours
etl::chrono::minutes
etl::chrono::seconds
etl::chrono::milliseconds
etl::chrono::microseconds
etl::chrono::nanoseconds
```
## duration_cast
```cpp
template <typename TToDuration, typename TRep, typename TPeriod>
ETL_CONSTEXPR14
TToDuration duration_cast(const etl::chrono::duration<TRep, TPeriod>& d)
ETL_NOEXCEPT
```
**Description**
Converts from one duration type to another.