This function converts financial year variables back into 201617 format.
See also
Other format:
format_ay(),
format_ay_reverse(),
format_fy()
Examples
format_fy_reverse("2016-17")
#> [1] "201617"
format_fy_reverse(c("2016-17", "2017-18"))
#> [1] "201617" "201718"
