PHP_FUNCTION(array_change_key_case)

 {

     zval *array, *entry;

     zend_string *string_key;

     zend_string *new_key;

     zend_ulong num_key;

     zend_long change_to_upper=;

     if (zend_parse_parameters(ZEND_NUM_ARGS(), "a|l", &array, &change_to_upper) == FAILURE) {

         return;

     }

     array_init_size(return_value, zend_hash_num_elements(Z_ARRVAL_P(array)));

     ZEND_HASH_FOREACH_KEY_VAL(Z_ARRVAL_P(array), num_key, string_key, entry) {

         if (!string_key) { // 数组键值为数字索引，将数组元素更新到return_value

             entry = zend_hash_index_update(Z_ARRVAL_P(return_value), num_key, entry);

         } else { // 数组键值为字符串

             // 字符串键值大小写转换

             if (change_to_upper) {

                 new_key = php_string_toupper(string_key);

             } else {

                 new_key = php_string_tolower(string_key);

             }

             // 将数组元素更新到return_value

             entry = zend_hash_update(Z_ARRVAL_P(return_value), new_key, entry);

             // 释放zend_string, 如果引用数位0，则释放内存。

             zend_string_release(new_key);

         }

         // 增加引用

         zval_add_ref(entry);

     } ZEND_HASH_FOREACH_END();

 }