Brief analysis of php natsort kernel function Page 1/2

Brief analysis of php natsort kernel function Page 1/2_PHP Tutorial

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Release： 2016-07-21 15:45:15

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Official manual (http://us.php.net/manual/en/function.natsort.php)

Copy code The code is as follows:

bool natsort ( array &$array ) 
This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort()) can be seen in the example below.

According to the official The manual also gives you something like this:

img1.png img2.png img10.png img12.png

Obviously this is great for sorting similar filenames. Judging from the results, this natural algorithm should remove the non-numeric parts of the head and tail, and then sort the remaining numeric parts. Whether it is true or not, let's take a look at the PHP source code.

Copy code The code is as follows:

//The relevant code extracted from ext/standard/array.c is as follows
static int php_array_natural_general_compare(const void *a, const void *b, int fold_case) /* {{{ */
{
Bucket *f, *s;
zval *fval, *sval;
zval first, second;
int result;
f = *((Bucket **) a);
s = *((Bucket **) b);
fval = *(( zval **) f->pData);
sval = *((zval **) s->pData);
first = *fval;
second = *sval;
if (Z_TYPE_P(fval) != IS_STRING) {
            zval_copy_ctor(&first);                                                zval_copy_ctor(&second );
convert_to_string(&second);
}
result = strnatcmp_ex(Z_STRVAL(first), Z_STRLEN(first), Z_STRVAL(second), Z_STRLEN(second), fold_case);
if (Z_TYPE_P (fval) != IS_STRING) {
zval_dtor(&first);
}
if (Z_TYPE_P(sval) != IS_STRING) {
zval_dtor(&second);
}
return result;
}
/* }}} */
static int php_array_natural_compare(const void *a, const void *b TSRMLS_DC) /* {{{ */
{
return php_array_natural_general_compare (a, b, 0);
}
/* }}} */
static void php_natsort(INTERNAL_FUNCTION_PARAMETERS, int fold_case) /* {{{ */
{
zval * array;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a", &array) == FAILURE) {
return;
}
if (fold_case) {
if (zend_hash_ sort(Z_ARRVAL_P (array), zend_qsort, php_array_natural_case_compare, 0 TSRMLS_CC) == FAILURE) {
                                                                   y), zend_qsort, php_array_natural_compare, 0 TSRMLS_CC) == FAILURE) {
                   return; &array_arg)
Sort an array using natural sort */
PHP_FUNCTION(natsort)
{
php_natsort(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
}
/* }}} */

Although this is the first time to view the core code of PHP, with many years of experience in reading code, it is easy to find that the core of this natural sorting algorithm is the function: strnatcmp_ex (located in the ext/standard/strnatcmp.c file).