Description:
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on the number_format page (http://us2.php.net/number_format) the parameters for it are listed as:

string number_format  ( float $number  [, int $decimals  [, string $dec_point  ]], string $thousands_sep  )

that is wrong, it suggests that when two parameters are given its $number, $thousands_sep), its not, instead like most functions it works left to right, with the exception that there is no valid form with three parameters, that means it should look like this

string number_format  ( float $number  [, int $decimals  [, string $dec_point, string $thousands_sep]])

that would indicate that its one two, for 4 parameters

and to quote from the docs on this issue, 'All optional parameters are seen in [ brackets ].' (http://us2.php.net/manual/en/about.prototypes.php), $thousands_sep is obviously optional but not in brackets

Reproduce code:
---------------
$a = 12345678.901;
echo number_format($a,2);
//12,345,678.90

//the prototype suggest this may be valid, though the docs below it say its wrong
echo number_format($a, 2, 'x');
//PHP Warning:  Wrong parameter count for number_format() in XXX- on line 5

echo number_format($a, 2, '.', ',');
//12,345,678.90

//this is wrong, but according to the docs should be correct
echo number_format($a,' ');        
//12,345,679