R: missing in action with dates/factors - r

Question

I'm bit lost in all those formatting and can't make my age function works, I'm not sure where format option applied to source or destination, my goal is to attach AGE column, dx$BIRTH_DATE define exactly like in my source data, factor in this format I can not change it. I don't want to use lubridate for now, as i need to migrate it to diff env. is it possible.
Thanks much for ur help!!
Mario
age_years <- function(from, to)
{
lt <- as.POSIXlt(c(from, to))
age <- lt$year[2] - lt$year[1]
mons <- lt$mon + lt$mday/50
if(mons[2] < mons[1]) age <- age -1
age
}
today <- Sys.Date() #,format="%m/%d/%Y")
class(today)
age_years("1988-06-30", "2003-07-12")
age_years("1988-06-30", date) ### doesn't work ???
as.character(dx$BIRTH_DATE)
as.Date(dx$BIRTH_DATE)
dx <- data.frame(ID = factor(c(1,2,3)), BIRTH_DATE = c("1/11/1953","2/12/1977","3/13/2000"), FEM = (c(11,22,33)))
dx
str(dx)
### <#>><
dx$AGE <- age_years(as.Date(dx$BIRTH_DATE), today) ## Age=1 ?????

Answer 1

Using your code here is a solution for you. You had 2 major problems, first your BirthDate format was not being declared (as noted by Pierre) second you were calling only the second and first year to declare the age, rather than using the entire dataframe. Now from and to are turned into vectors to define ages. Hope this helps!
age_years <- function(from, to)
{
from <- as.POSIXlt(from)
to<- as.POSIXlt(to)
age <- to$year - from$year
mons <- from$mon + from$mday/50
if(mons[2] < mons[1]) age <- age -1
age
}
today <- Sys.Date() #,format="%m/%d/%Y")
dx <- data.frame(ID = factor(c(1,2,3)), BIRTH_DATE = c("1/11/1953","2/12/1977","3/13/2000"), FEM = (c(11,22,33)))
dx$AGE <- age_years(from=as.Date(dx$BIRTH_DATE,format = "%m/%d/%Y"), to=today)
> dx
ID BIRTH_DATE FEM AGE
1 1 1/11/1953 11 62
2 2 2/12/1977 22 38
3 3 3/13/2000 33 15