gmp_hamdist
(PHP 4 >= 4.0.4, PHP 5)
gmp_hamdist — Hamming distance
Description
int gmp_hamdist
( resource
$a
, resource $b
)
Returns the hamming distance between a and
b. Both operands should be non-negative.
Parameters
Return Values
A GMP number resource.
Examples
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";
?>
The above example will output:
6 6
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Математические расширения
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- gmp_abs
- gmp_add
- gmp_and
- gmp_clrbit
- gmp_cmp
- gmp_com
- gmp_div_q
- gmp_div_qr
- gmp_div_r
- gmp_div
- gmp_divexact
- gmp_export
- gmp_fact
- gmp_gcd
- gmp_gcdext
- gmp_hamdist
- gmp_import
- gmp_init
- gmp_intval
- gmp_invert
- gmp_jacobi
- gmp_legendre
- gmp_mod
- gmp_mul
- gmp_neg
- gmp_nextprime
- gmp_or
- gmp_perfect_square
- gmp_popcount
- gmp_pow
- gmp_powm
- gmp_prob_prime
- gmp_random_bits
- gmp_random_range
- gmp_random_seed
- gmp_random
- gmp_root
- gmp_rootrem
- gmp_scan0
- gmp_scan1
- gmp_setbit
- gmp_sign
- gmp_sqrt
- gmp_sqrtrem
- gmp_strval
- gmp_sub
- gmp_testbit
- gmp_xor
Коментарии
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.