A brief discussion of PHP source code 13: Introduction to array_change_key_case and array_chunk

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Brief Discussion PHP source code 13: Introduction to array_change_key_case, array_chunk

array_change_key_case

(PHP 4 >= 4.2.0, PHP 5)
array_change_key_case — Return string key names in all lowercase Or an uppercase array
Description

array array_change_key_case (array input [, int case])

array_change_key_case() Changes all key names in the input array to all lowercase or uppercase. Changes are made based on the latter option case argument. Two constants can be used here, CASE_UPPER and CASE_LOWER. The default value is CASE_LOWER. This function does not change the numeric index.
Seeing this function, I think it should traverse the hash table where the array is located, and then convert its corresponding key value into uppercase or lowercase (if it is a string key value)
After reading it, there are some differences. The program is to add one to the reference of each array element

array_chunk
(PHP 4 >= 4.2.0, PHP 5)
array_chunk — Split an array into multiple
Description

array array_chunk (array input, int size [, bool preserve_keys])

array_chunk() splits an array into multiple arrays, where the number of cells in each array is determined by size . The last array may have a few fewer elements. The resulting array is a cell in a multidimensional array, with indexes starting from zero.
Set the optional parameter preserve_keys to TRUE to enable PHP to retain the original key names in the input array. If you specify FALSE, each result array will be indexed with a new number starting from zero. The default value is FALSE.

Program implementation instructions:

  array_init(return_value);    //    初始化返回值 数组
  zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(input), &pos);
  while (zend_hash_get_current_data_ex(Z_ARRVAL_P(input), (void**)&entry, &pos) == SUCCESS) {      //    遍历HASH TABLE/* 如果不存在，则创建并初始化chunk */
   if (!chunk) {
   MAKE_STD_ZVAL(chunk);array_init(chunk);}
   /* 给数组元素的引用加一，相当于 *entry->refcount++; */
   zval_add_ref(entry);
   if (preserve_keys) {    //    保留键值
   key_type = zend_hash_get_current_key_ex(Z_ARRVAL_P(input), &str_key,&str_key_len, &num_key, 0, &pos);    //    取元素的key值类型，此值是要所元素的nKeyLength属性判断 
   if (key_type == HASH_KEY_IS_STRING) {    //    字符串类型add_assoc_zval_ex(chunk, str_key, str_key_len, *entry);
   } else {
   add_index_zval(chunk, num_key, *entry);}
   } else {
   add_next_index_zval(chunk, *entry);    //    给返回的子数组添加元素} 
   if (!(++current % size)) {    //    如果达到分割的界限，则将分割出来创建的子数组添加到返回数组中，并将子数组置为NULl
   add_next_index_zval(return_value, chunk);
   chunk = NULL;}zend_hash_move_forward_ex(Z_ARRVAL_P(input), &pos);    //    下一个元素}
   if (chunk) {add_next_index_zval(return_value, chunk);    //    剩余的元素}

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