gmp_* functions don't accept strings with a leading '+':
<?php
echo gmp_strval(gmp_init('+42')); #0
echo gmp_strval(gmp_add('42', '+42')); #42
echo bcadd('+42', '+42'); #84
?>
gmp_add
(PHP 4 >= 4.0.4, PHP 5)
gmp_add — Add numbers
Description
resource gmp_add ( resource $a, resource $b )Add two GMP numbers. The result will be a GMP number representing the sum of the arguments.
Příklad 596. gmp_add() example
<?php
$sum = gmp_add("123456789012345", "76543210987655");
echo gmp_strval($sum) . "\n";
?>
The printout of the above program will be:
200000000000000
gmp_add
charlie at oblivion dot cz
18-Feb-2007 04:54
18-Feb-2007 04:54
