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
For more information on the new features and other changes, you can read the NEWS file, or the UPGRADING filefor a complete list of upgrading notes. These files can also be found in the release archive.（文章来自南京欣才PHP培训机构）
