$number
[, int $decimals = 0
] )
This function accepts either one, two, or four parameters (not three):
If only one parameter is given,
number will be formatted without decimals,
but with a comma (",") between every group of thousands.
If two parameters are given, number will
be formatted with decimals decimals with a
dot (".") in front, and a comma (",") between every group of
thousands.
If all four parameters are given, number
will be formatted with decimals decimals,
dec_point instead of a dot (".") before
the decimals and thousands_sep instead of
a comma (",") between every group of thousands.

