这个函数是我第一次看手册的时候，没看明白是怎么回事，所以有必要记录一下
用法
bool array_multisort ( array &$arr [, mixed $arg = SORT_ASC [, mixed $arg = SORT_REGULAR [, mixed $... ]]] )
array_multisort() 可以用来一次对多个数组进行排序，或者根据某一维或多维对多维数组进行排序。
关联（string）键名保持不变，但数字键名会被重新索引。
排序顺序标志：
-
SORT_ASC- 按照上升顺序排序 -
SORT_DESC- 按照下降顺序排序
排序类型标志：
-
SORT_REGULAR- 将项目按照通常方法比较 -
SORT_NUMERIC- 将项目按照数值比较 -
SORT_STRING- 将项目按照字符串比较
每个数组之后不能指定两个同类的排序标志。每个数组后指定的排序标志仅对该数组有效 - 在此之前为默认值 SORT_ASC 和 SORT_REGULAR。
输入数组被当成一个表的列并以行来排序——这类似于 SQL 的 ORDER BY 子句的功能。第一个数组是要排序的主要数组。数组中的行（值）比较为相同的话就按照下一个输入数组中相应值的大小来排序，依此类推。
本函数的参数结构有些不同寻常，但是非常灵活。第一个参数必须是一个数组。接下来的每个参数可以是数组或者是下面列出的排序标志。
示例一：
<?php
function my_sort($arrays, $sort_key, $sort_order = SORT_ASC, $sort_type = SORT_NUMERIC)
{
if (is_array($arrays)) {
foreach ($arrays as $array) {
if (is_array($array)) {
$key_arrays[] = $array[$sort_key];
} else {
return false;
}
}
} else {
return false;
}
array_multisort($key_arrays, $sort_order, $sort_type, $arrays);
return $arrays;
} $person = array(
array('id' => 1, 'name' => 'fj', 'weight' => 100, 'height' => 180),
array('id' => 2, 'name' => 'tom', 'weight' => 53, 'height' => 150),
array('id' => 3, 'name' => 'jerry', 'weight' => 120, 'height' => 156),
array('id' => 4, 'name' => 'bill', 'weight' => 110, 'height' => 190),
array('id' => 5, 'name' => 'linken', 'weight' => 80, 'height' => 200),
array('id' => 6, 'name' => 'madana', 'weight' => 95, 'height' => 110),
array('id' => 7, 'name' => 'jordan', 'weight' => 70, 'height' => 170)
); $person = my_sort($person, 'name', SORT_ASC, SORT_STRING); var_dump($person); ?>
结果
array (size=7)
0 =>
array (size=4)
'id' => int 4
'name' => string 'bill' (length=4)
'weight' => int 110
'height' => int 190
1 =>
array (size=4)
'id' => int 1
'name' => string 'fj' (length=2)
'weight' => int 100
'height' => int 180
2 =>
array (size=4)
'id' => int 3
'name' => string 'jerry' (length=5)
'weight' => int 120
'height' => int 156
3 =>
array (size=4)
'id' => int 7
'name' => string 'jordan' (length=6)
'weight' => int 70
'height' => int 170
4 =>
array (size=4)
'id' => int 5
'name' => string 'linken' (length=6)
'weight' => int 80
'height' => int 200
5 =>
array (size=4)
'id' => int 6
'name' => string 'madana' (length=6)
'weight' => int 95
'height' => int 110
6 =>
array (size=4)
'id' => int 2
'name' => string 'tom' (length=3)
'weight' => int 53
'height' => int 150
示例二：
<?php
$grade = array(
"score" => array(70, 95, 70.0, 60, "70"),
"name" => array("Zhang San", "Li Si", "Wang Wu", "Zhao Liu", "Liu Qi")
);
array_multisort($grade["score"], SORT_NUMERIC, SORT_DESC,
// 将分数作为数值，由高到低排序
$grade["name"], SORT_STRING, SORT_ASC);
// 将名字作为字符串，由小到大排序
var_dump($grade);
结果
array (size=2)
'score' =>
array (size=5)
0 => int 95
1 => string '70' (length=2)
2 => float 70
3 => int 70
4 => int 60
'name' =>
array (size=5)
0 => string 'Li Si' (length=5)
1 => string 'Liu Qi' (length=6)
2 => string 'Wang Wu' (length=7)
3 => string 'Zhang San' (length=9)
4 => string 'Zhao Liu' (length=8)
我看来，这算一个比较神奇的函数了
/* {{{ proto bool array_multisort(array ar1 [, SORT_ASC|SORT_DESC [, SORT_REGULAR|SORT_NUMERIC|SORT_STRING|SORT_NATURAL|SORT_FLAG_CASE]] [, array ar2 [, SORT_ASC|SORT_DESC [, SORT_REGULAR|SORT_NUMERIC|SORT_STRING|SORT_NATURAL|SORT_FLAG_CASE]], ...])
Sort multiple arrays at once similar to how ORDER BY clause works in SQL */
PHP_FUNCTION(array_multisort)
{
zval*** args;
zval*** arrays;
Bucket*** indirect;
Bucket* p;
HashTable* hash;
int argc;
int array_size;
int num_arrays = 0;
int parse_state[MULTISORT_LAST]; /* 0 - flag not allowed 1 - flag allowed */
int sort_order = PHP_SORT_ASC;
int sort_type = PHP_SORT_REGULAR;
int i, k;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "+", &args, &argc) == FAILURE) {
return;
}
/* Allocate space for storing pointers to input arrays and sort flags. */
arrays = (zval ***)ecalloc(argc, sizeof(zval **));
for (i = 0; i < MULTISORT_LAST; i++) {
parse_state[i] = 0;
ARRAYG(multisort_flags)[i] = (int *)ecalloc(argc, sizeof(int));
}
/* Here we go through the input arguments and parse them. Each one can
* be either an array or a sort flag which follows an array. If not
* specified, the sort flags defaults to PHP_SORT_ASC and PHP_SORT_REGULAR
* accordingly. There can't be two sort flags of the same type after an
* array, and the very first argument has to be an array. */
for (i = 0; i < argc; i++) {
if (Z_TYPE_PP(args[i]) == IS_ARRAY) {
/* We see the next array, so we update the sort flags of
* the previous array and reset the sort flags. */
if (i > 0) {
ARRAYG(multisort_flags)[MULTISORT_ORDER][num_arrays - 1] = sort_order;
ARRAYG(multisort_flags)[MULTISORT_TYPE][num_arrays - 1] = sort_type;
sort_order = PHP_SORT_ASC;
sort_type = PHP_SORT_REGULAR;
}
arrays[num_arrays++] = args[i];
/* Next one may be an array or a list of sort flags. */
for (k = 0; k < MULTISORT_LAST; k++) {
parse_state[k] = 1;
}
} else if (Z_TYPE_PP(args[i]) == IS_LONG) {
switch (Z_LVAL_PP(args[i]) & ~PHP_SORT_FLAG_CASE) {
case PHP_SORT_ASC:
case PHP_SORT_DESC:
/* flag allowed here */
if (parse_state[MULTISORT_ORDER] == 1) {
/* Save the flag and make sure then next arg is not the current flag. */
sort_order = Z_LVAL_PP(args[i]) == PHP_SORT_DESC ? -1 : 1;
parse_state[MULTISORT_ORDER] = 0;
} else {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or sorting flag that has not already been specified", i + 1);
MULTISORT_ABORT;
}
break;
case PHP_SORT_REGULAR:
case PHP_SORT_NUMERIC:
case PHP_SORT_STRING:
case PHP_SORT_NATURAL:
#if HAVE_STRCOLL
case PHP_SORT_LOCALE_STRING:
#endif
/* flag allowed here */
if (parse_state[MULTISORT_TYPE] == 1) {
/* Save the flag and make sure then next arg is not the current flag. */
sort_type = Z_LVAL_PP(args[i]);
parse_state[MULTISORT_TYPE] = 0;
} else {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or sorting flag that has not already been specified", i + 1);
MULTISORT_ABORT;
}
break;
default:
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is an unknown sort flag", i + 1);
MULTISORT_ABORT;
break;
}
} else {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Argument #%d is expected to be an array or a sort flag", i + 1);
MULTISORT_ABORT;
}
}
/* Take care of the last array sort flags. */
ARRAYG(multisort_flags)[MULTISORT_ORDER][num_arrays - 1] = sort_order;
ARRAYG(multisort_flags)[MULTISORT_TYPE][num_arrays - 1] = sort_type;
/* Make sure the arrays are of the same size. */
array_size = zend_hash_num_elements(Z_ARRVAL_PP(arrays[0]));
for (i = 0; i < num_arrays; i++) {
if (zend_hash_num_elements(Z_ARRVAL_PP(arrays[i])) != array_size) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Array sizes are inconsistent");
MULTISORT_ABORT;
}
}
/* If all arrays are empty we don't need to do anything. */
if (array_size < 1) {
for (k = 0; k < MULTISORT_LAST; k++) {
efree(ARRAYG(multisort_flags)[k]);
}
efree(arrays);
efree(args);
RETURN_TRUE;
}
/* Create the indirection array. This array is of size MxN, where
* M is the number of entries in each input array and N is the number
* of the input arrays + 1. The last column is NULL to indicate the end
* of the row. */
indirect = (Bucket ***)safe_emalloc(array_size, sizeof(Bucket **), 0);
for (i = 0; i < array_size; i++) {
indirect[i] = (Bucket **)safe_emalloc((num_arrays + 1), sizeof(Bucket *), 0);
}
for (i = 0; i < num_arrays; i++) {
k = 0;
for (p = Z_ARRVAL_PP(arrays[i])->pListHead; p; p = p->pListNext, k++) {
indirect[k][i] = p;
}
}
for (k = 0; k < array_size; k++) {
indirect[k][num_arrays] = NULL;
}
/* Do the actual sort magic - bada-bim, bada-boom. */
zend_qsort(indirect, array_size, sizeof(Bucket **), php_multisort_compare TSRMLS_CC);
/* Restructure the arrays based on sorted indirect - this is mostly taken from zend_hash_sort() function. */
HANDLE_BLOCK_INTERRUPTIONS();
for (i = 0; i < num_arrays; i++) {
hash = Z_ARRVAL_PP(arrays[i]);
hash->pListHead = indirect[0][i];;
hash->pListTail = NULL;
hash->pInternalPointer = hash->pListHead;
for (k = 0; k < array_size; k++) {
if (hash->pListTail) {
hash->pListTail->pListNext = indirect[k][i];
}
indirect[k][i]->pListLast = hash->pListTail;
indirect[k][i]->pListNext = NULL;
hash->pListTail = indirect[k][i];
}
p = hash->pListHead;
k = 0;
while (p != NULL) {
if (p->nKeyLength == 0)
p->h = k++;
p = p->pListNext;
}
hash->nNextFreeElement = array_size;
zend_hash_rehash(hash);
}
HANDLE_UNBLOCK_INTERRUPTIONS();
/* Clean up. */
for (i = 0; i < array_size; i++) {
efree(indirect[i]);
}
efree(indirect);
for (k = 0; k < MULTISORT_LAST; k++) {
efree(ARRAYG(multisort_flags)[k]);
}
efree(arrays);
efree(args);
RETURN_TRUE;
}
待续
参考：http://php.net/manual/zh/function.array-multisort.php