even though the manual says the json extension is enabled by default and compiled into the core, I had to do a "yum install php-json" on centos 8 running php 7.2
自 PHP 5.2.0 起，JSON 扩展默认内置并编译进了 PHP。
安装此 PECL 扩展相关的信息可在手册中标题为 PECL 扩展的安装章节中找到。更多信息如新的发行版本、下载、源文件、 维护人员信息及变更日志等，都在此处： » https://pecl.php.net/package/json
even though the manual says the json extension is enabled by default and compiled into the core, I had to do a "yum install php-json" on centos 8 running php 7.2
on CentOS php 5.5.13 had to:
yum install php55u-pecl-jsonc php55u-pecl-jsonc-devel
On Ubuntu 13.10 you have to install this extension first (PHP 5.5.3):
apt-get install php5-json
(Don't forget to restart web server.)
On RHEL5/CentOS5 add the EPEL repository (http://fedoraproject.org/wiki/EPEL).
After that, installation is as simple as:
sudo yum install php-pecl-json
On gentoo, need the USE flag "json" to compile into php
On one server I use (FreeBSD 6.3; PHP 5.2.6 as module in Apache 2.2.10), PHP was compiled with the '--disable-all' configuration option. Consequently, there exists a secondary configuration file -- /usr/local/php5/etc/extensions.ini -- in which the line
; extension=json.so
must be uncommented (delete the semicolon) and Apache restarted for these functions to be available.