Creates a GMP number from an integer or string. String
representation can be decimal or hexadecimal. In the latter case,
the string should start with 0x.
Optional parameter base is available since
PHP 4.1.0.
Замечание:
It is not necessary to call this function if you want to use
integer or string in place of GMP number in GMP functions, like
gmp_add(). Function arguments are
automatically converted to GMP numbers, if such conversion is
possible and needed, using the same rules as
gmp_init().