PHP :
variable handling function-

1.empty
2.gettype
3.is array
4.is bool
5.is integer
6.is set
7.print-r
8.serialize
9.unserialize
10.unset
11.var-dump.

string function-
1.addclass
2.addslashes
3.crypt
4.implode
5.md5
6.nl2br
7.str-shuffle
8.str-word-count
9.str-split
10.stelenght
11.strlower
12.stripper
13.subst-lower
14.subs-count
15.uc-first
16.uc-word