What is a token in php?

Various parts of the PHP language are represented internally by tokens. A code snippet that contains an invalid sequence of tokens may lead to errors like Parse error: syntax error, unexpected token "==", expecting "[" in script.php on line 10." where token == is internally represented by T_IS_EQUAL.

The following table lists all tokens. They are also available as PHP constants.

Note: Usage of T_* constants

T_* constants values are automatically generated based on PHP's underlying parser infrastructure. This means that the concrete value of a token may change between two PHP versions. This means that your code should never rely directly on the original T_* values taken from PHP version X.Y.Z, to provide some compatibility across multiple PHP versions.

To make use of T_* constants across multiple PHP versions, undefined constants may be defined by the user [using big numbers like 10000] with an appropriate strategy that will work with both PHP versions and T_* values.

or %> escaping from HTML T_COALESCE ?? comparison operators T_COALESCE_EQUAL ??= assignment operators [available as of PHP 7.4.0] T_COMMENT // or #, and /* */ comments T_CONCAT_EQUAL .= assignment operators T_CONST const class constants T_CONSTANT_ENCAPSED_STRING "foo" or 'bar' string syntax T_CONTINUE continue continue T_CURLY_OPEN {$ complex variable parsed syntax T_DEC -- incrementing/decrementing operators T_DECLARE declare declare T_DEFAULT default switch T_DIR __DIR__ magic constants T_DIV_EQUAL /= assignment operators T_DNUMBER 0.12, etc. floating point numbers T_DO do do..while T_DOC_COMMENT /** */ PHPDoc style comments T_DOLLAR_OPEN_CURLY_BRACES ${ complex variable parsed syntax T_DOUBLE_ARROW => array syntax T_DOUBLE_CAST [real], [double] or [float] type-casting T_DOUBLE_COLON :: see T_PAAMAYIM_NEKUDOTAYIM below T_ECHO echo echo T_ELLIPSIS ... function arguments T_ELSE else else T_ELSEIF elseif elseif T_EMPTY empty empty[] T_ENCAPSED_AND_WHITESPACE " $a" constant part of string with variables T_ENDDECLARE enddeclare declare, alternative syntax T_ENDFOR endfor for, alternative syntax T_ENDFOREACH endforeach foreach, alternative syntax T_ENDIF endif if, alternative syntax T_ENDSWITCH endswitch switch, alternative syntax T_ENDWHILE endwhile while, alternative syntax T_ENUM enum Enumerations [available as of PHP 8.1.0] T_END_HEREDOC   heredoc syntax T_EVAL eval[] eval[] T_EXIT exit or die exit[], die[] T_EXTENDS extends extends, classes and objects T_FILE __FILE__ magic constants T_FINAL final Final Keyword T_FINALLY finally Exceptions T_FN fn arrow functions [available as of PHP 7.4.0] T_FOR for for T_FOREACH foreach foreach T_FUNCTION function functions T_FUNC_C __FUNCTION__ magic constants T_GLOBAL global variable scope T_GOTO goto goto T_HALT_COMPILER __halt_compiler[] __halt_compiler T_IF if if T_IMPLEMENTS implements Object Interfaces T_INC ++ incrementing/decrementing operators T_INCLUDE include[] include T_INCLUDE_ONCE include_once[] include_once T_INLINE_HTML   text outside PHP T_INSTANCEOF instanceof type operators T_INSTEADOF insteadof Traits T_INTERFACE interface Object Interfaces T_INT_CAST [int] or [integer] type-casting T_ISSET isset[] isset[] T_IS_EQUAL == comparison operators T_IS_GREATER_OR_EQUAL >= comparison operators T_IS_IDENTICAL === comparison operators T_IS_NOT_EQUAL != or comparison operators T_IS_NOT_IDENTICAL !== comparison operators T_IS_SMALLER_OR_EQUAL classes and objects T_NULLSAFE_OBJECT_OPERATOR ?-> classes and objects T_OPEN_TAG