# time_length: Compute the exact length of a time span.

## Description

Compute the exact length of a time span.

## Usage

time_length(x, unit = "second")# S4 method for Interval
time_length(x, unit = "second")

## Arguments

x

a duration, period, difftime or interval

unit

a character string that specifies with time units to use

## Value

the length of the interval in the specified unit. A negative number
connotes a negative interval or duration

## Details

When `x`

is an `Interval-class`

object and
`unit`

are years or months, `timespan_length`

takes into account
the fact that all months and years don't have the same number of days.

When `x`

is a `Duration-class`

, `Period-class`

or `difftime`

object, length in months or years is based on their
most common lengths in seconds (see `timespan`

).

## Examples

# NOT RUN {
int <- interval(ymd("1980-01-01"), ymd("2014-09-18"))
time_length(int, "week")
# Exact age
time_length(int, "year")
# Age at last anniversary
trunc(time_length(int, "year"))
# Example of difference between intervals and durations
int <- interval(ymd("1900-01-01"), ymd("1999-12-31"))
time_length(int, "year")
time_length(as.duration(int), "year")
# }