Variable Types

A variable type defines values what can be represented by that variable, as well as the amount of memory the variable will occupy.

Integer types

BOOL

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Range:	0 or 1
Bit Depth:	1-bit unsigned integer

A Boolean value is either false or true. In Flowcode, this means 0 or 1, respectively. On download to an embedded target, this may take up 1 byte or a single bit of a byte, depending on the compiler and the optimisation level.

Boolean values are used typically as flags to indicate something needs to happen, has happened, or to control a function.

BYTE

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Range:	0 to 255
Bit Depth:	8-bit unsigned integer

A byte is the smallest storage unit most processors are able to read from in a single instruction.

A byte can be used to store a single value or its bits may be used as flags, almost like a compact array of BOOLs.

The value stored in a byte can only be positive.

INT

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Range:	-32768 to 32767
Bit Depth:	16-bit signed integer

A signed int uses the top most bit of the binary value to indicate a positive or negative value, 0b0XXXXXXXXXXXXXXX being a positive value and 0b1XXXXXXXXXXXXXXX being a negative value.

The negative values are stored in 2's compliment form with 0b1000000000000000 = -32768 and 0b11111111111111111 = -1

UINT

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Range:	0 to 65535
Bit Depth:	16-bit unsigned integer

An unsigned value allows for the use of all of the bits allowing for a positive value with twice the range as the signed counterpart.

LONG

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Range:	-21474836648 to 21474836647
Bit Depth:	32-bit signed integer

A 32-bit integer is useful for processing larger values and most integer-arithmetic uses found in embedded devices.

A signed long uses the top most bit of the binary value to indicate a positive or negative value. See INT for details.

32-bit calculations require additional maths libraries, by default calculations will only be 16-bit. By using a 32-bit variable the additional libraries will be used.

ULONG

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Range:	0 to 4294967295
Bit Depth:	32-bit unsigned integer

An unsigned value allows for the use of all of the bits allowing for a positive value with twice the range as the signed counterpart.

32-bit calculations require additional maths libraries, by default calculations will only be 16-bit. By using a 32-bit variable the additional libraries will be used.

STRING

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Range:	0 to 255
Bit Depth:	8-bit array of integers. Default size of the array is 20 but can be adjusted as required.

A string consists of an array of 8-bit values, usually containing values with ASCII encoding which maps alphanumeric characters to the numeric values.

For example "Hello" is the same as {72,101,108,108,111,0}

Strings are automatically terminated with a 0 or null byte, this indicates the end of valid data when using string functions.

String is a typecasting keyword in Flowcode and so cannot be used for variable, property or component names.

Numeric values and variables can easily be converted to a string by using the keyword sting before the variable.

e.g. StringVar1 = "Temperature: " + string IntVar1

Details on the string functions are available here.

FLOAT

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Range:	±1.175494 × 10−38 to ±3.402824 × 1038
Bit Depth:	32-bit floating point

The range of a single-precision floating-point number is approximately ±1.175494 × 10−38 to ±3.402824 × 1038.

Floating point single-precision numbers are 32-bit approximations of real numbers which can represent a much wider range of values than an integer can, but at a loss of accuracy over large ranges.

Floating point calculations require additional maths libraries, by default calculations will only be 16-bit integer. By using a floating point variable the additional libraries will be used.

When defining floating point constants e.g. 1, it is important to let the C compiler know that the value is intended for use as a floating point value otherwise an integer calculation will take precedent.

To tell the C compiler the constant value is floating point simply use for example 1.0 as your constant.

Float is a typecasting keyword in Flowcode and so cannot be used for variable, property or component names.

Mathematical operations such as a = b + c will be processed as an integer calculation if a, b or c are integer values.

for example you would expect 2.5 * 2 to equal 5 but in the world of integers the calculation only sees 2.5 * 2 = 4, the real portion of the number is lost.

To fix this you must instead use 2.5 * 2.0 = 5

The keyword float can be used to force a calculation to be done using floating point maths instead of integer maths.

e.g. FloatVar1 = FloatVar2 + float IntVar1

Using the float keyword or changing the constant value to for example 35.0 would force the value to be recognised as a floating point type variable.

HANDLE

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Range:	Undefined
Bit Depth:	32-bit unsigned value

An object handle is used to reference a more complicated piece of data (such as a file, Flowcode component or block of text) whose internal format is not known. Flowcode provides many simulation macros that use handles to easily pass data around.

In an embedded context, a handle can be thought of as a pointer to memory, except Flowcode manages the handles so referencing a non-existent handle will not cause any fatal errors.

A handle value of zero is considered null and invalid to Flowcode.