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3.1 Built-in Data Types

The standard built-in data types are real and complex scalars and matrices, ranges, character strings, a data structure type, and cell arrays. Additional built-in data types may be added in future versions. If you need a specialized data type that is not currently provided as a built-in type, you are encouraged to write your own user-defined data type and contribute it for distribution in a future release of Octave.

The data type of a variable can be determined and changed through the use of the following functions.

— Built-in Function: class (expr)
— Built-in Function: class (s, id)
— Built-in Function: class (s, id, p, ...)

Return the class of the expression expr or create a class with fields from structure s and name (string) id. Additional arguments name a list of parent classes from which the new class is derived.

— Function File: isa (x, class)

Return true if x is a value from the class class.

— Function File: cast (val, type)

Convert val to data type type.

See also: int8, uint8, int16, uint16, int32, uint32, int64, uint64, double.

— Loadable Function: typecast (x, type)

Convert from one datatype to another without changing the underlying data. The argument type defines the type of the return argument and must be one of 'uint8', 'uint16', 'uint32', 'uint64', 'int8', 'int16', 'int32', 'int64', 'single' or 'double'.

An example of the use of typecast on a little-endian machine is 

          x = uint16 ([1, 65535]);
          typecast (x, 'uint8')
          => [   0,   1, 255, 255]

See also: cast, swapbytes.

— Function File: swapbytes (x)

Swaps the byte order on values, converting from little endian to big endian and vice versa. For example 

          swapbytes (uint16 (1:4))
          => [   256   512   768  1024]

See also: typecast, cast.