Core Predefined Constants These constants are defined by the PHP core. This includes PHP, the Zend engine, and SAPI modules. PHP_VERSION (string) The current PHP version as a string in "major.minor.release[extra]" notation. PHP_MAJOR_VERSION (int) The current PHP "major" version as an integer (e.g., int(5) from version "5.2.7-extra"). PHP_MINOR_VERSION (int) The current PHP "minor" version as an integer (e.g., int(2) from version "5.2.7-extra"). PHP_RELEASE_VERSION (int) The current PHP "release" version as an integer (e.g., int(7) from version "5.2.7-extra"). PHP_VERSION_ID (int) The current PHP version as an integer, useful for version comparisons (e.g., int(50207) from version "5.2.7-extra"). PHP_EXTRA_VERSION (string) The current PHP "extra" version as a string (e.g., '-extra' from version "5.2.7-extra"). Often used by distribution vendors to indicate a package version. PHP_ZTS (int) PHP_DEBUG (int) PHP_MAXPATHLEN (int) The maximum length of filenames (including path) supported by this build of PHP. PHP_OS (string) The operating system PHP was built for. PHP_OS_FAMILY (string) The operating system family PHP was built for. One of 'Windows', 'BSD', 'Darwin', 'Solaris', 'Linux' or 'Unknown'. Available as of PHP 7.2.0. PHP_SAPI (string) The Server API for this build of PHP. See also php_sapi_name. PHP_EOL (string) The correct 'End Of Line' symbol for this platform. PHP_INT_MAX (int) The largest integer supported in this build of PHP. Usually int(2147483647) in 32 bit systems and int(9223372036854775807) in 64 bit systems. PHP_INT_MIN (int) The smallest integer supported in this build of PHP. Usually int(-2147483648) in 32 bit systems and int(-9223372036854775808) in 64 bit systems. Usually, PHP_INT_MIN === ~PHP_INT_MAX. PHP_INT_SIZE (int) The size of an integer in bytes in this build of PHP. PHP_FLOAT_DIG (int) Number of decimal digits that can be rounded into a float and back without precision loss. Available as of PHP 7.2.0. PHP_FLOAT_EPSILON (float) Smallest representable positive number x, so that x + 1.0 != 1.0. Available as of PHP 7.2.0. PHP_FLOAT_MIN (float) Smallest representable positive floating point number. If you need the smallest representable negative floating point number, use - PHP_FLOAT_MAX. Available as of PHP 7.2.0. PHP_FLOAT_MAX (float) Largest representable floating point number. Available as of PHP 7.2.0. DEFAULT_INCLUDE_PATH (string) PEAR_INSTALL_DIR (string) PEAR_EXTENSION_DIR (string) PHP_EXTENSION_DIR (string) The default directory where to look for dynamically loadable extensions (unless overridden by extension_dir). Defaults to PHP_PREFIX (or PHP_PREFIX . "\\ext" on Windows). PHP_PREFIX (string) The value was set to at configure. On Windows, it is the value was set to at configure. PHP_BINDIR (string) The value was set to at configure. On Windows, it is the value was set to at configure. PHP_BINARY (string) Specifies the PHP binary path during script execution. PHP_MANDIR (string) Specifies where the manpages were installed into. PHP_LIBDIR (string) PHP_DATADIR (string) PHP_SYSCONFDIR (string) PHP_LOCALSTATEDIR (string) PHP_CONFIG_FILE_PATH (string) PHP_CONFIG_FILE_SCAN_DIR (string) PHP_SHLIB_SUFFIX (string) The build-platform's shared library suffix, such as "so" (most Unixes) or "dll" (Windows). PHP_FD_SETSIZE (string) The maximum number of file descriptors for select system calls. Available as of PHP 7.1.0. E_ERROR (int) Error reporting constant E_WARNING (int) Error reporting constant E_PARSE (int) Error reporting constant E_NOTICE (int) Error reporting constant E_CORE_ERROR (int) Error reporting constant E_CORE_WARNING (int) Error reporting constant E_COMPILE_ERROR (int) Error reporting constant E_COMPILE_WARNING (int) Error reporting constant E_USER_ERROR (int) Error reporting constant E_USER_WARNING (int) Error reporting constant E_USER_NOTICE (int) Error reporting constant E_RECOVERABLE_ERROR (int) Error reporting constant. E_DEPRECATED (int) Error reporting constant. E_USER_DEPRECATED (int) Error reporting constant. E_ALL (int) Error reporting constant E_STRICT (int) Error reporting constant __COMPILER_HALT_OFFSET__ (int) &true; (bool) See Booleans. &false; (bool) See Booleans. &null; (null) See Null. PHP_WINDOWS_EVENT_CTRL_C (int) A Windows CTRL+C event. Available as of PHP 7.4.0 (Windows only). PHP_WINDOWS_EVENT_CTRL_BREAK (int) A Windows CTRL+BREAK event. Available as of PHP 7.4.0 (Windows only). See also: Magic constants.