SPHINX似乎沒有跟上PHP7的更新腳步，還好有大陸的朋友提供了解決方法[1][2]，到目前為止很有效。

OS

CentOS Linux release 7.3.1611 (Core)
PHP 7.0.18 (cli) (built: Apr 15 2017 07:09:11) ( NTS )
mysql  Ver 15.1 Distrib 5.5.52-MariaDB, for Linux (x86_64) using readline 5.1  (Mysql客戶端)

安裝 SPHINX

# wget http://sphinxsearch.com/files/sphinx-2.3.1-1.rhel7.x86_64.rpm
# yum install sphinx-2.3.1-1.rhel7.x86_64.rpm

安裝 PHP library

下載
http://git.php.net/?p=pecl/search_engine/sphinx.git;a=snapshot;h=339e123acb0ce7beb2d9d4f9094d6f8bcf15fb54;sf=tgz

PHP 5.X請下載這個
http://git.php.net/?p=pecl/search_engine/sphinx.git;a=snapshot;h=7d9b13f64621bb0011743110b77e9f30c2f43b9b;sf=tgz

# tar zxvf sphinx-339e123.tar.gz
# cd sphinx-339e123
# phpize
# ./configure
# make
# make install

安裝完後自動會產生
/etc/php.d/sphinx.ini

如果沒有自動產生，就手動新增，裡面只有一行

extension=sphinx.so

/usr/lib64/php/modules/sphinx.so

# systemctl restart httpd

檢查是否有啟動
# php -m | grep 'sphinx'
sphinx

SPHINX設定

設定開機啟動
# systemctl enable searchd

啟動SPHINX
# systemctl start searchd

關閉SPHINX
# systemctl stop searchd

SPHINX狀態
# systemctl status searchd

錯誤排除

1. 程序起動如果失敗，請檢查  /var/run 中有沒有 sphinx的目錄，權限皆為 sphinx:sphinx

延伸閱讀

安裝SPHINX支援中文@新精讚

PHP for sphinx 函式庫安裝@新精讚

參考資料

[1] https://www.ddhigh.com/php/2017/02/28/php7-compile-sphinx-extension.html

[2] https://www.36nu.com/post/205.html