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 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.

//从ext/standard/array.c抽取的相关代码如下
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);
convert_to_string(&first);
}
if (Z_TYPE_P(sval) != IS_STRING) {
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) {
return;
}
} else {
if (zend_hash_sort(Z_ARRVAL_P(array),PHP_array_natural_compare,0 TSRMLS_CC) == FAILURE) {
return;
}
}
RETURN_TRUE;
}
/* }}} */
/* {{{ proto void natsort(array &array_arg)
Sort an array using natural sort */
PHP_FUNCTION(natsort)
{
PHP_natsort(INTERNAL_FUNCTION_PARAM_PASSTHRU,0);
}
/* }}} */

/* {{{ compare_right
*/
static int
compare_right(char const **a,char const *aend,char const **b,char const *bend)
{
int bias = 0;
/* The longest run of digits wins. That aside,the greatest
value wins,but we can't know that it will until we've scanned
both numbers to know that they have the same magnitude,so we
remember it in BIAS. */
for(;; (*a)++,(*b)++) {
if ((*a == aend || !isdigit((int)(unsigned char)**a)) &&
(*b == bend || !isdigit((int)(unsigned char)**b)))
return bias;
else if (*a == aend || !isdigit((int)(unsigned char)**a))
return -1;
else if (*b == bend || !isdigit((int)(unsigned char)**b))
return +1;
else if (**a < **b) {
if (!bias)
bias = -1;
} else if (**a > **b) {
if (!bias)
bias = +1;
}
}
return 0;
}
/* }}} */
/* {{{ compare_left
*/
static int
compare_left(char const **a,char const *bend)
{
/* Compare two left-aligned numbers: the first to have a
different value wins. */
for(;; (*a)++,(*b)++) {
if ((*a == aend || !isdigit((int)(unsigned char)**a)) &&
(*b == bend || !isdigit((int)(unsigned char)**b)))
return 0;
else if (*a == aend || !isdigit((int)(unsigned char)**a))
return -1;
else if (*b == bend || !isdigit((int)(unsigned char)**b))
return +1;
else if (**a < **b)
return -1;
else if (**a > **b)
return +1;
} return 0;
}
/* }}} */
/* {{{ strnatcmp_ex
* call in array.c: strnatcmp_ex(Z_STRVAL(first),fold_case);
*/
PHPAPI int strnatcmp_ex(char const *a,size_t a_len,char const *b,size_t b_len,int fold_case)
{
char ca,cb;
char const *ap,*bp;
char const *aend = a + a_len,
*bend = b + b_len;
int fractional,result;
if (a_len == 0 || b_len == 0)
return a_len - b_len;
ap = a;
bp = b;
while (1) {
ca = *ap; cb = *bp;
/* skip over leading spaces or zeros */
while (isspace((int)(unsigned char)ca) || (ca == '0' && (ap+1 < aend) && (*(ap+1)!='.')))
ca = *++ap;
while (isspace((int)(unsigned char)cb) || (cb == '0' && (bp+1 < bend) && (*(bp+1)!='.')))
cb = *++bp;
/* process run of digits */
if (isdigit((int)(unsigned char)ca) && isdigit((int)(unsigned char)cb)) {
fractional = (ca == '0' || cb == '0');
if (fractional)
result = compare_left(&ap,aend,&bp,bend);
else
result = compare_right(&ap,bend);
if (result != 0)
return result;
else if (ap == aend && bp == bend)
/* End of the strings. Let caller sort them out. */
return 0;
else {
/* Keep on comparing from the current point. */
ca = *ap; cb = *bp;
}
}
if (fold_case) {
ca = toupper((int)(unsigned char)ca);
cb = toupper((int)(unsigned char)cb);
}
if (ca < cb)
return -1;
else if (ca > cb)
return +1;
++ap; ++bp;
if (ap >= aend && bp >= bend)
/* The strings compare the same. Perhaps the caller
will want to call strcmp to break the tie. */
return 0;
else if (ap >= aend)
return -1;
else if (bp >= bend)
return 1;
}
}
/* }}} */

while (isspace((int)(unsigned char)ca) || (ca == '0' && (ap+1 < aend) && (*(ap+1)!='.')))
ca = *++ap;
while (isspace((int)(unsigned char)cb) || (cb == '0' && (bp+1 < bend) && (*(bp+1)!='.')))
cb = *++bp;