Boolean

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Boolean

Standard data type

Syntax

Dim variable As Boolean

Description

Boolean data type. Can hold the values True 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 False and 1 to indicate True.
• For a practical definition, we must consider, yet again, additional factors. The most significant factor is that the hardware (processor) on which code is executed does not directly support a 1-bit data type; the smallest register or memory size we can work with is 8-bits or 1-byte.
• 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 such that 'not 0' produces '-1'.
• Nevertheless the definition under the hood for a FB boolean remains an 1-bit integer, zero extended to fill larger integer 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 True value or False value, regardless of the underlying details.*

Remarks

Dialect Differences

• Not available in the -lang qb dialect unless referenced with the alias __Boolean.

Differences from QB

• New to FreeBASIC

See also

• CBool
• True
• False
• Table with variable types overview, limits and suffixes

Examples

Dim boolvar As Boolean

boolvar = True

Print "boolvar = ", boolvar

Output:

boolvar =     true

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Category: Standard Data Types
Kind: keyword

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.