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PHP 7.0.2 has been released on php.net on 7th January 2016, and is also available for CentOS/RHEL 6.7 and 7.1 at Webtatic via Yum in it’s testing repository.
PEAR installer now supports PHP 7.0, however most pecl libraries will not support it as well without their maintainers adding compatibility, so only pecl libraries that do support it will be in the Webtatic repository.

PHP 7.0.0 comes with new version of the Zend Engine with features such as (incomplete list):
Improved performance: PHP 7 is up to twice as fast as PHP 5.6
Consistent 64-bit support
Many fatal errors are now Exceptions
Removal of old and unsupported SAPIs and extensions
The null coalescing operator (??)
Combined comparison Operator (<=>)
Return Type Declarations
Scalar Type Declarations
Anonymous Classes

To see what else has been added, check out the Migrating from PHP 5.6.x to PHP 7.0.x.
To install, first you must add the Webtatic EL yum repository information corresponding to your CentOS/RHEL version to yum:
CentOS/RHEL 7.x:
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpmrpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm

CentOS/RHEL 6.x:
rpm -Uvh https://mirror.webtatic.com/yum/el6/latest.rpm

Now you can install PHP 7.0 (along with an opcode cache) by doing:
yum install php70w php70w-opcache

This will install the mod_php SAPI for PHP, however there are other sapis such as php-fpm (via php70w-fpm package). Read on below for more information about the available SAPIs
If you would like to upgrade php to this version it is recommended that you first check that your system will support the upgrade, e.g. making sure any CPanel-like software can run after the upgrade.
Unless you know what you are doing, it is risky upgrading an existing system. It’s much safer to do this by provisioning a separate server to perform the upgrade as a fresh install instead.
If you know what you are doing, you can upgrade PHP by:
yum install yum-plugin-replace yum replace php-common --replace-with=php70w-common

It will likely give you a message “WARNING: Unable to resolve all providers …”. This is normal, and you can continue by tying “y“. You will be given a chance to see what packages will be installed and removed before again being given a chance to confirm.
SAPIs – different runtime environments of PHP
mod_php NTS
(non-thread safety) Contained in the php56w package, this SAPI integrates into Apache Httpd (2.2.* on RHEL/CentOS 6, 2.4.* on RHEL/CentOS 7). It is the standard SAPI for use with httpd prefork mpm (the default mode httpd is ran under. It is not thread-safe, but doesn’t need to be due to prefork not using threads. It’s located at /usr/lib[64]/httpd/modules/libphp7.so
cli
Contained in the php70w-cli package, this SAPI allows running scripts from the command-line, and also has a built-in web server for development-use. Located at /usr/bin/php
fpm
Contained in the php70w-fpm package, fpm (FastCGI Process Manager) is a scalable FastCGI process, which acts similar to how Httpd prefork mpm works managing it’s forks. Located at /usr/sbin/php-fpm, it is controlled using the /etc/init.d/php-fpm service script
phpdbg
Contained in the php70w-phpdbg package, phpdbg has the ability to debug scripts using breakpoints from the command-line, and also supports remote-debugging using an external Java client for remote communication.
embedded
Contained in the php70w-embedded package, this SAPI allows embedding PHP in other applications. It’s library is located at /usr/lib[64]/libphp7.so
cgi, fastcgi
Contained in the php70w-cli package, these SAPIs are not recommended for use, but are available where needed. They both exist in the binary at /usr/bin/php-cgi.
mod_php TS
(thread safety) Contained in the php70w package, this SAPI integrates into Apache Httpd (2.2.* on RHEL/CentOS 6, 2.4.* on RHEL/CentOS 7). It is the standard SAPI for use with httpd worker mpm. It’s supposed to be thread-safe, but can’t guarantee to be, and certainly not under additional PHP extensions. It’s better to use FastCGI SAPIs than this one. It’s located at /usr/lib[64]/httpd/modules/libphp7-zts.so
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