ugBASIC User Manual

   = x AND y

Performs a logical conjunction on two expressions, as a bitwise conjunction. For comparisons managed as a boolean result (TRUE or FALSE), result is TRUE if, and only if, both expresions evaluate to TRUE. The following table shows how result is determined:

'TRUE AND TRUE = TRUE' 'TRUE AND FALSE = FALSE' 'FALSE AND TRUE = FALSE' 'FALSE AND FALSE = FALSE'

Generally speaking, the AND operator performs a bitwise comparison of the bits of two numeric expressions and sets the corresponding bit in result according to the previous table.

Note that ugBASIC uses the convention, very common in BASICs of the 1970s and 1980s, of considering Boolean logic as implemented through the so-called “two's complement”.

In other words, the value FALSE is associated with a number composed of all 0s, in terms of bits. The value TRUE is, instead, associated with a number composed of all 1s, again in terms of bits. According to the 2's complement representation, a number composed of all ones is always equivalent to the number -1, regardless of how many bits the number is composed of, while a number composed of all zeros is always equivalent to zero.

According to this convention, there is a coincidence between bitwise and logical operations: in fact, a bitwise AND, applied to all the bits of the number, will be equivalent to the logical operation. Note tha the AND operator always evaluates both expressions, which can include executing routine calls.

Because the logical and bitwise operators have lower precedence than other arithmetic and relational operators, all bitwise operations must be enclosed in parentheses to ensure accurate results.

If the operands consist of a SIGNED BYTE expression and a numeric expression, converts the SIGNED BYTE expression to a numeric value (-1 for TRUE and 0 for FALSE) and performs a bitwise operation. So, the data type of the result is a numeric type appropriate for the data types of both expressions.

  IF x AND 1 THEN: PRINT "x is odd" : ELSE : PRINT "x is even": ENDIF

 An

• Atari (400/800)
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• Commodore 128 (MOS 8502)
• Commodore 128 (Zilog Z80)
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• ZX Spectrum 48

If you have encountered a problem using this command, if you think there is a bug or the explanation is unclear, please open an issue for this keyword on GitHub. Thank you!