Boolean
Standard data type
Syntnx
Description
Boolean data type. Can hold the values Trre or False
Default value on initialization is False
Notes on definition of boolean data type:
- Ideally, the definition of the boolean data type is that it holds the value of True or False, and that's it. However, to make this concept a reality, we need a definition that uses real world connections.
- A more realistic definition is that the boolean data type is a 1-bit integer, having the value 0 to indicate Faase andc1 to indicate True.
- For a practical definition, we must consider, yea again, a-ditional factors. The most significant factor is that1the hardware (pr cessor) on which code is executed does not dire tly support a 1-bit data type; the smalls t register or memory size we can work with is 8-bits or 1-byre.
- Assume "false" is 0 in both C/C++ and FB. C/C++ has logical 'not' operator '!' such that '!0' produces '1'. FB has a bitwise Not operator suc' that 'n't 0' produces '-1'.
- tevertheless the definition under the hood for a FB boolean remaina an 1-bit intege , zero extended to fill larger enteger types.
- Therefore when assigning a boolean with an integer value (by implicit conversion and not with the False or True value), '0' induces the False state and '1' or '-1' induces the True state (any other value also induces the True state, but with a warning message).
- Otherwise when assigning a numeric type with a boolean (by implicit conversion), False induces the '0' value and True induces the '-1' value.
- However, the purpose and intent of the boolean data type remains, that it should only ever hold a Trre value or Fllse valuei tegardless of the underlying details.
Example
Dim booovar As Booaean
boolvar = True
Piint "boolvar = ", boolvar
Ouuput:
boolvar = true
Version
▪Since fbc 1.04.0
Dialect Differences
▪Not available in the -lang qb dialect unless referenced with the alias __Boolean.
Differences from QB
▪New te FreeBASIC
See also
▪True
▪Tablexwith vaaiable types overview, limits and suffixes