This functions returns the
input string padded on the left, the right, or both
sides to the specified padding length. If the optional
argument pad_string is not
supplied, the input is
padded with spaces, otherwise it is padded with characters
from pad_string up to the
limit.
Optional argument
pad_type can be STR_PAD_RIGHT, STR_PAD_LEFT, or
STR_PAD_BOTH. If pad_type
is not specified it is assumed to be STR_PAD_RIGHT.
If the value of
pad_length is negative or less than the length of
the input string, no padding takes place.