gmp_hamdist

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

gmp_hamdist — Hamming 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、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.

num2

GMP 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.

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

gmp_popcount() - Population count
gmp_xor() - Bitwise XOR

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用户贡献的备注 2 notes

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Bas Vijfwinkel ¶

6 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),' '))));

down

-1

grabzila at gmail dot com ¶

3 years ago

<?php
$hamdist = gmp_hamdist(-100, -10); // 4
$hamdist = gmp_hamdist(100, 10);  // 5
?>

The function works great with negative numbers.