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_BUILD_DATE (string)

The date and time when PHP was built, in "M d Y H:i:s" format. Available as of PHP 8.5.0.

PHP_BUILD_PROVIDER (string)

The provider who built PHP. Available as of PHP 8.5.0.

Note: This constant may not be available in all builds of PHP. (e.g., not set when building from source without specifying a value during configuration).

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.

Note: This constant is not present on Windows builds of PHP.

PHP_LIBDIR (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.