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.
Note: 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().