Correct syntax for reading and writing with CSV file

If I have the command to edit the input file, do I still need to split it and define each array or can the whole file just be read, split it, then add the commands below?  If that's not the right approach can you explain to me the right direction.
"null found" unless $array[5];        #####null check with exception of
splice(@array, -1);                   ###(removes the last element)

The other question i have is how do I assign specific ranges to the mm/dd/yy format?  For example, I want to have an mm/dd/yy format in which for january the range is between 1-31 while in february it's between 1-29 (leap year)?Start Free Trial