How to install phalcon on php

How to install phalcon in php is always unsuccessful & nbsp; follow the prompts on the official website to first put it in the ext folder & nbsp; then in php. add extensionphp_phalcon.dll in ini and restart wamp to prompt this error... then I will download another php5.dll and it will prompt this kind of error ------ solution ------------------ how does my & nbsp; php install phalcon on php?
Installation fails. follow the instructions on the official website.
Put it in the ext folder, add extension = php_phalcon.dll in php. ini, and restart wamp to prompt this error...

Then I download another php5.dll and it prompts this error again.

------ Solution --------------------
My php is 5.4.20
Php_phalcon.dll is 5.4.12.0
No problem

print_r(preg_grep('/^phalcon/i', get_declared_classes()));

Array
(
    [145] => Phalcon\Exception
    [146] => Phalcon\Db\Adapter
    [147] => Phalcon\DI\Injectable
    [148] => Phalcon\DI
    [149] => Phalcon\Forms\Element
    [150] => Phalcon\Mvc\Model\Validator
    [151] => Phalcon\Validation\Validator
    [152] => Phalcon\Cache\Backend
    [153] => Phalcon\Db\Adapter\Pdo
    [154] => Phalcon\Db\Dialect
    [155] => Phalcon\Mvc\Model\MetaData
    [156] => Phalcon\Annotations\Adapter
    [157] => Phalcon\Logger\Formatter
    [158] => Phalcon\Logger\Adapter
    [159] => Phalcon\Flash
    [160] => Phalcon\Mvc\Model\Behavior
    [161] => Phalcon\Dispatcher
    [162] => Phalcon\Mvc\Model\Resultset
    [163] => Phalcon\Mvc\View\Engine
    [164] => Phalcon\Mvc\Model\Exception
    [165] => Phalcon\Assets\Resource
    [166] => Phalcon\Config
    [167] => Phalcon\Session\Adapter
    [168] => Phalcon\Acl\Adapter
    [169] => Phalcon\Translate\Adapter
    [170] => Phalcon\DI\FactoryDefault
    [171] => Phalcon\Mvc\Router
    [172] => Phalcon\Tag
    [173] => Phalcon\Acl
    [174] => Phalcon\Db
    [175] => Phalcon\Cache\Exception
    [176] => Phalcon\Cache\Multiple
    [177] => Phalcon\Cache\Backend\Apc
    [178] => Phalcon\Cache\Backend\File
    [179] => Phalcon\Cache\Backend\Mongo
    [180] => Phalcon\Cache\Backend\Memory
    [181] => Phalcon\Cache\Backend\Memcache
    [182] => Phalcon\Cache\Frontend\Output
    [183] => Phalcon\Cache\Frontend\None
    [184] => Phalcon\Cache\Frontend\Json
    [185] => Phalcon\Cache\Frontend\Base64
    [186] => Phalcon\Cache\Frontend\Data
    [187] => Phalcon\Tag\Select
    [188] => Phalcon\Tag\Exception
    [189] => Phalcon\Paginator\Exception
    [190] => Phalcon\Paginator\Adapter\Model
    [191] => Phalcon\Paginator\Adapter\QueryBuilder
    [192] => Phalcon\Paginator\Adapter\NativeArray
    [193] => Phalcon\Validation
    [194] => Phalcon\Validation\Message
    [195] => Phalcon\Validation\Exception
    [196] => Phalcon\Validation\Message\Group
    [197] => Phalcon\Validation\Validator\Email
    [198] => Phalcon\Validation\Validator\Regex
    [199] => Phalcon\Validation\Validator\Identical
    [200] => Phalcon\Validation\Validator\Between
    [201] => Phalcon\Validation\Validator\Confirmation
    [202] => Phalcon\Validation\Validator\PresenceOf
    [203] => Phalcon\Validation\Validator\ExclusionIn
    [204] => Phalcon\Validation\Validator\StringLength
    [205] => Phalcon\Validation\Validator\InclusionIn
    [206] => Phalcon\Db\Index
    [207] => Phalcon\Db\Column
    [208] => Phalcon\Db\Adapter\Pdo\Sqlite
    [209] => Phalcon\Db\Adapter\Pdo\Mysql
    [210] => Phalcon\Db\Adapter\Pdo\Oracle
    [211] => Phalcon\Db\Adapter\Pdo\Postgresql
    [212] => Phalcon\Db\Dialect\Oracle
    [213] => Phalcon\Db\Dialect\Mysql
    [214] => Phalcon\Db\Dialect\Sqlite