types

CONCEPT
    types

DESCRIPTION

    Variables can have the following types:

    o int       An integer. Normally 32 bits or 64 bits signed, yielding
                a range of at least -2,147,483,648 to 2,147,483,647. The
                exact available range is given by the predefined
                macros __INT_MIN__ and __INT_MAX__.

                Integer values can be specified in decimal, in
                sedecimal when preceded by '0x' (e.g. 0x11), binary
                when preceeded by '0b' (e.g. 0b00010001), octal when
                preceded by '0o' (e.g. 0o21) and as character
                yielding the charset value for the character as the number
                to use (e.g. '0' yields 48 on ASCII machines).

                Character values are enclosed in single-quotes ('),
                with the sequence ''' returning the single-quote
                itself. Instead of the literal character an
                escape-sequence can be written between the
                single-quotes:
                  \N   : the character code N in decimal
                  \0xN : the character code N in sedecimal
                  \xN  : the character code N in sedecimal
                  \0oN : the character code N in octal
                  \0bN : the character code N in binary
                  \a   : BEL (0x07)
                  \b   : Backspace (0x08)
                  \t   : Tab (0x09)
                  \e   : Escape (0x1b)
                  \n   : Newline (0x0a)
                  \f   : Formfeed (0x0c)
                  \r   : Carriage Return (0x0d)
                  \<other character>: the given character

    o status    OUTDATED - status was planned to be an optimized
                boolean format, but this was never actually
                implemented. status does work; however, since it
                is only an alias for type 'int', just use int.

    o string    Strings in lpc are true strings, not arrays of characters
                as in C (and not pointers to strings). Strings are
                mutable -- that is, the contents of a string can be
                modified as needed.

                The text of a string is written between double-quotes
                ("). A string can written over several lines when the
                lineends are escaped (like a macro), however a better
                solution is to write one string per line and let the
                gamedriver concatenate them.

                String text typically consists of literal characters,
                but escape-sequences can be used instead of
                characters:
                  \<CR>     : Carriage Return (0x0d)
                  \<CR><LF> : ignored
                  \<LF>     : ignored
                  \<LF><CR> : ignored

                  \N        : the character code N in decimal
                  \0xN      : the character code N in sedecimal
                  \xN       : the character code N in sedecimal
                  \0oN      : the character code N in octal
                  \0bN      : the character code N in binary
                  \uNNNN    : Unicode character N in sedicimal
                  \UNNNNNNNN: Unicode character N in sedicimal
                  \a        : BEL (0x07)
                  \b        : Backspace (0x08)
                  \t        : Tab (0x09)
                  \e        : Escape (0x1b)
                  \n        : Newline (0x0a)
                  \f        : Formfeed (0x0c)
                  \r        : Carriage Return (0x0d)
                  \"        : The double quote (")
                  \<other character>: the given character

                Adjacent string literals are automatically
                concatenated by the driver when the LPC program is
                compiled. String literals joined with '+' are
                concatenated by the LPC compiler as well.

    o bytes     Byte sequences are similar to strings. They offer
                the same operations, but cannot be mixed with strings.

                Byte sequence literals are written between double-quotes
                prefixed with a 'b' (e.g. b""). Adjacent byte sequence
                literals are automatically concatenated.

                The text is allowed to consist of ASCII characters
                (equivalent to bytes 0-127) and escape-sequences
                just like strings, with the exception of the \u and \U
                unicode escape sequences.

    o object    Pointer to an object. Objects are always passed by
                reference. The type specification can include a program
                name that is a mandatory inherit of the given object:

                    object "/std/room" var;

                This program name is only verified during runtime when
                runtime type checks are activated. See pragma(LPC).

    o lwobject  Pointer to an lightweight object. Similar to objects
                lightweight objects are always passed by reference.
                The type specification can include a program name that
                is a mandatory inherit of the given object:

                    lwobject "/lwo/data" var;

                This program name is only verified during runtime when
                runtime type checks are activated. See pragma(LPC).

    o array     Pointer to a vector of values, which could also
                be an alist. Arrays take the form ({ n1, n2, n3 })
                and may contain any type or a mix of types. Arrays
                are always passed by reference. Note that the size
                of arrays in LPC, unlike most programming languages,
                CAN be changed at run-time.

    o mapping   An 'associative array' consisting of values indexed by
                keys. The indices can be any kind of datatype.
                Mappings take the form ([ key1: value1, key2: value2 ]).
                By default, mappings are passed by reference.

    o closure   References to executable code, both to local
                functions, efuns and to functions compiled at
                run-time ("lambda closures").

    o coroutine Holds the execution state of an asynchronous function.

    o symbol    Identifier names, which in essence are quoted strings.
                They are used to compute lambda closures, e.g. instead
                of ({..., 'ident, ... }) you can write declare a
                'symbol' variable foo, compute a value for it, and then
                create the closure as ({ ..., foo, ... })

    o float     A floating point number in the absolute range
                __FLOAT_MIN__ to __FLOAT_MAX__ (typically 2.2e-308 to
                1.8e+308). Floating point numbers are signified by
                a '.' appearing, e.g. '1' is integer 1, but '1.' is
                floating-point 1 .

    o mixed     A variable allowed to take a value of any type (int,
                string, object, array, mapping, float or closure).

    o struct    A collection of values. See structs(LPC).

    o union     A range of types, either of which the variable
                can contain at runtime. See unions(LPC).

    All uninitialized variables have the value 0.

    The type of a variable is really only for documentation. Unless
    you define #pragma strong_types or rtt_checks, variables can
    actually be of any type and has no effect at all on the program.
    However, it's extremely bad style to declare one type but use
    another, so please try to avoid this.

    A pointer to a destructed object will always have the value 0.


HISTORY
    The types lwobject and coroutine were introduced in LDMud 3.6.5.


SEE ALSO
    alists(LPC), arrays(LPC), mappings(LPC), closures(LPC), coroutines(LPC),
    objects(LPC), structs(LPC), unions(LPC), typeof(E), get_type_info(E),
    inheritance(LPC), pragma(LPC), modifiers(LPC), escape(LPC)