PHPerKaigi 2024

gmp_hamdist

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_hamdistHamming distance

说明

gmp_hamdist(GMP|int|string $num1, GMP|int|string $num2): int

Returns the hamming distance between num1 and num2. Both operands should be non-negative.

参数

num1

GMP 对象或 int ,或数字string

It should be positive.

num2

GMP 对象或 int ,或数字string

It should be positive.

返回值

The hamming distance between num1 and num2, as an int.

示例

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

参见

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User Contributed Notes 2 notes

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4
Bas Vijfwinkel
5 years ago
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),' '))));
up
-1
grabzila at gmail dot com
2 years ago
<?php
$hamdist
= gmp_hamdist(-100, -10); // 4
$hamdist = gmp_hamdist(100, 10); // 5
?>

The function works great with negative numbers.
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