Dates, times, datetimes are all numerics. Dates is number of days since cuttoff, times number of seconds since midnight.
To convert text to number we use the input() function (as opposed to the put() function to go from number to character). This is:
input(<text>,<format>)
So text can be any string, and format is one of the informats supplied by SAS or built by yourself - all in the documentation.
So:
data want;
set have;
num_date=input(char_date,ddmmyy8.);
format num_date date9.;
run;