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.

ZEND_THREAD_SAFE (bool )

Indicates whether the current build of PHP is thread safe.

ZEND_DEBUG_BUILD (bool )

Indicates whether the current build of PHP is a debug build.

PHP_ZTS (bool ) Alias of ZEND_THREAD_SAFE

Indicates whether the current build of PHP is thread safe.

PHP_DEBUG (bool ) Alias of ZEND_DEBUG_BUILD

Indicates whether the current build of PHP is a debug build.

DEBUG_BACKTRACE_PROVIDE_OBJECT (int )

Populate the "object" index.

DEBUG_BACKTRACE_IGNORE_ARGS (int )

Don't include the argument information for functions in the stack trace.

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 --prefix was set to at configure. On Windows, it is the value --with-prefix was set to at configure.

PHP_BINDIR (string )

The value --bindir was set to at configure. On Windows, it is the value --with-prefix was set to at configure.

PHP_SBINDIR (string )

The value --sbindir was set to at configure. On Windows, it is the value --with-prefix was set to at configure. Available as of PHP 8.4.0.

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 (int )

The maximum number of file descriptors for select system calls. Available as of PHP 7.1.0.

E_ERROR (int )

E_WARNING (int )

E_PARSE (int )

E_NOTICE (int )

E_CORE_ERROR (int )

E_CORE_WARNING (int )

E_COMPILE_ERROR (int )

E_COMPILE_WARNING (int )

E_USER_ERROR (int )

E_USER_WARNING (int )

E_USER_NOTICE (int )

E_RECOVERABLE_ERROR (int )

E_DEPRECATED (int )

E_USER_DEPRECATED (int )

E_ALL (int )

E_STRICT (int )

Error reporting constants

__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).

PHP_CLI_PROCESS_TITLE (bool )

Indicates whether the setting and getting of the process title is available. Available only under the CLI SAPI.

STDERR (resource )

An already opened stream to stderr. Available only under the CLI SAPI.

STDIN (resource )

An already opened stream to stdin. Available only under the CLI SAPI.

STDOUT (resource )

An already opened stream to stdout. Available only under the CLI SAPI.

See also: Magic constants.

Standard Predefined Constants

All constants from core extensions are defined in PHP by default.