gmp_hamdist

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

gmp_hamdistHamming distance

说明

gmp_hamdist ( GMP $a , GMP $b ) : int

Returns the hamming distance between a and b. Both operands should be non-negative.

参数

a

PHP 5.5 之前为 GMP 数值资源,PHP 5.6 之后为 GMP 对象或数字,或可以转为数字的字符串。

It should be positive.

b

PHP 5.5 之前为 GMP 数值资源,PHP 5.6 之后为 GMP 对象或数字,或可以转为数字的字符串。

It should be positive.

返回值

The hamming distance between a and b, as an int.

范例

Example #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";
?>

以上例程会输出:

6
6

参见

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User Contributed Notes 1 note

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1
Bas Vijfwinkel
2 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),' '))));
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