预定义常量
内核预定义常量
这些常量在 PHP 的内核中定义。它包含 PHP、Zend 引擎和 SAPI 模块。
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PHP_VERSION(string) - The current PHP version as a string in "major.minor.release[extra]" notation.
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PHP_MAJOR_VERSION(integer) - The current PHP "major" version as an integer (e.g., int(5) from version "5.2.7-extra"). Available since PHP 5.2.7.
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PHP_MINOR_VERSION(integer) - The current PHP "minor" version as an integer (e.g., int(2) from version "5.2.7-extra"). Available since PHP 5.2.7.
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PHP_RELEASE_VERSION(integer) - The current PHP "release" version as an integer (e.g., int(7) from version "5.2.7-extra"). Available since PHP 5.2.7.
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PHP_VERSION_ID(integer) - The current PHP version as an integer, useful for version comparisons (e.g., int(50207) from version "5.2.7-extra"). Available since PHP 5.2.7.
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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. Available since PHP 5.2.7.
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PHP_ZTS(integer) - Available since PHP 5.2.7.
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PHP_DEBUG(integer) - Available since PHP 5.2.7.
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PHP_MAXPATHLEN(integer) - The maximum length of filenames (including path) supported by this build of PHP. Available since PHP 5.3.0.
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PHP_OS(string) - The operating system PHP was built for.
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PHP_OS_FAMILY(string) - The operating system family PHP was built for. Either of 'Windows', 'BSD', 'Darwin', 'Solaris', 'Linux' or 'Unknown'. Available as of PHP 7.2.0.
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PHP_SAPI(string) - The Server API for this build of PHP.参见 php_sapi_name()。
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PHP_EOL(string) - The correct 'End Of Line' symbol for this platform.自 PHP 5.0.2 起可用
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PHP_INT_MAX(integer) - The largest integer supported in this build of PHP. Usually int(2147483647).自 PHP 5.0.5 起可用
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PHP_INT_MIN(integer) - The smallest integer supported in this build of PHP. Usually int(-2147483648) in 32 bit systems and int(-9223372036854775808) in 64 bit systems. Available since PHP 7.0.0. Usually, PHP_INT_MIN === ~PHP_INT_MAX.
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PHP_INT_SIZE(integer) - The size of an integer in bytes in this build of PHP. 自 PHP 5.0.5 起可用
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PHP_FLOAT_DIG(integer) - Number of decimal digits that can be rounded into a float and back without precision loss. Available as of PHP 7.2.0.
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PHP_FLOAT_EPSILON(float) - Smallest representable positive number x, so that x + 1.0 != 1.0. Available as of PHP 7.2.0.
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PHP_FLOAT_MIN(float) - Smallest representable floating point number. Available as of PHP 7.2.0.
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PHP_FLOAT_MAX(float) - Largest representable floating point number. Available as of PHP 7.2.0.
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DEFAULT_INCLUDE_PATH(string) -
PEAR_INSTALL_DIR(string) -
PEAR_EXTENSION_DIR(string) -
PHP_EXTENSION_DIR(string) -
PHP_PREFIX(string) - The value "--prefix" was set to at configure.
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PHP_BINDIR(string) - Specifies where the binaries were installed into.
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PHP_BINARY(string) - Specifies the PHP binary path during script execution. Available since PHP 5.4.
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PHP_MANDIR(string) - Specifies where the manpages were installed into. Available since PHP 5.3.7.
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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).
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PHP_FD_SETSIZE(string) - The maximum number of file descriptors for select system calls. Available as of PHP 7.1.0.
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E_ERROR(integer) - Error reporting constant
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E_WARNING(integer) - Error reporting constant
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E_PARSE(integer) - Error reporting constant
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E_NOTICE(integer) - Error reporting constant
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E_CORE_ERROR(integer) - Error reporting constant
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E_CORE_WARNING(integer) - Error reporting constant
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E_COMPILE_ERROR(integer) - Error reporting constant
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E_COMPILE_WARNING(integer) - Error reporting constant
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E_USER_ERROR(integer) - Error reporting constant
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E_USER_WARNING(integer) - Error reporting constant
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E_USER_NOTICE(integer) - Error reporting constant
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E_RECOVERABLE_ERROR(integer) - Error reporting constant. Available since PHP 5.2.0
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E_DEPRECATED(integer) - Error reporting constant. Available since PHP 5.3.0
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E_USER_DEPRECATED(integer) - Error reporting constant. Available since PHP 5.3.0
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E_ALL(integer) - Error reporting constant
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E_STRICT(integer) - Error reporting constant
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__COMPILER_HALT_OFFSET__(integer) - 自 PHP 5.1.0 起有效
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TRUE(boolean) - See Booleans.
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FALSE(boolean) - See Booleans.
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NULL(null) - See Null.
参见魔术常量。
标准预定义常量
所有在核心扩展 的常量是 PHP 默认定义的。