(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_hamdist — Hamming distance
Returns the hamming distance between num1 and
num2. Both operands should be non-negative.
num1GMP 对象、int 或 string，可以按照跟在 gmp_init() 中使用字符串并自动检测 base（即当 base 等于 0 时）相同的逻辑将其解释为数字。
It should be positive.
num2GMP 对象、int 或 string，可以按照跟在 gmp_init() 中使用字符串并自动检测 base（即当 base 等于 0 时）相同的逻辑将其解释为数字。
It should be positive.
The hamming distance between num1 and num2, as an int.
示例 #1 gmp_hamdist() example
<?php
$ham1 = gmp_init("1001010011", 2);
$ham2 = gmp_init("1011111100", 2);
echo gmp_hamdist($ham1, $ham2) . "\n";
/* hamdist is equivalent to: */
echo gmp_popcount(gmp_xor($ham1, $ham2)) . "\n";
?>以上示例会输出：
6 6
For those without gmp support :
$hamming_distance = count(array_diff_assoc(str_split($string1), str_split($string2)));
And if you are not sure if your strings have equal length :
$hamming_distance = count(array_diff_assoc(str_split(str_pad($string1,strlen($string2)-strlen($string1),' ')), str_split(str_pad($string2,strlen($string1)-strlen($string2),' '))));<?php
$hamdist = gmp_hamdist(-100, -10); // 4
$hamdist = gmp_hamdist(100, 10); // 5
?>
The function works great with negative numbers.