I am reading a date value from csv file.So the format will vary according to the date format of csv. How can I convert any date string to dd-mm-yyy HH:mm:ss ?
ED
See the anytime package whose anytime function does just that -- and without requiring a format string:
> inputs <- c("12/07/2017 10:11:12", "12/07/2017", "12-07-2017 10:11:12",
+ "07-12-2017", "2017-12-07 10:11:12", "2017-12-07")
> library(anytime)
> anytime(inputs)
[1] "2017-12-07 10:11:12 CST" "2017-12-07 00:00:00 CST"
[3] "2017-12-07 10:11:12 CST" "2017-07-12 00:00:00 CDT"
[5] "2017-12-07 10:11:12 CST" "2017-12-07 00:00:00 CST"
>
However, your requirement of accepting both d-m-y and m-d-y is not satisfiable. So you need to make a choice and supply an explicit format here.
In general, I highly recommend avoiding the ambiguity and sticking to y-m-d ISO formats. As a convenience to stubborn North American habits, anytime and anydata also accept m-d-y ordering but it is dangerous.
Again, only you can tell if 3-4-5 is April 3rd or March 4th, and you need to specify that.