(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gmp_init — Create GMP number
Creates a GMP number from an integer or string.
number
An integer or a string. The string representation can be decimal, hexadecimal or octal.
base
The base.
The base may vary from 2 to 36. If base is 0 (default value), the actual base is determined from the leading characters: if the first two characters are 0x or 0X, hexadecimal is assumed, otherwise if the first character is "0", octal is assumed, otherwise decimal is assumed.
Version  Description 

5.3.2 
The base was extended from 2 to 36, to
2 to 62 and 2 to 36.

Note:
To use the extended base introduced in PHP 5.3.2, then PHP must be compiled against GMP 4.2.0 or greater.
Example #1 Creating GMP number
<?php
$a = gmp_init(123456);
$b = gmp_init("0xFFFFDEBACDFEDF7200");
?>
Note:
It is not necessary to call this function in order to use integers or strings in place of GMP numbers in GMP functions (such as with gmp_add()). Function arguments are automatically converted to GMP numbers, if such conversion is possible and needed, using the same rules as gmp_init().