instruction boolean QB64 true o false

[_vince]

Here is a fun tip: if you want to toggle a variable between two values 'a' and 'b' then xor it by (a xor b),

z = 7
z = z xor (7 xor 19) '=19
z = z xor (7 xor 19) '=7
z = z xor (7 xor 19) '=19
z = z xor (7 xor 19) '=7
'... and so on

Code: [Select]

z = 7 'start value
a = 0

for i=1 to 10
? chr$(asc("T")*-(a<>0)+asc("F")*-(a=0))+chr$(asc("R")*-(a<>0)+asc("A")*-(a=0))+chr$(asc("U")*-(a<>0)+asc("L")*-(a=0))+chr$(asc("E")*-(a<>0)+asc("S")*-(a=0))+chr$(asc("E")*-(a=0)), a, z


z = z xor (7 xor 19)
a = a xor (0 xor not 0)
next


[Richard Frost]

var XOR 1 is faster, in theory, than var = 1 - var,
because only one register is involved. 

Vince's toggle method is neat, and new to me.  It
even works for flipping between 0 and 1.  But it
does incur 3 register loads and 2 register operations.

Speed doesn't much matter for normal programs, but
it sure does for things like chess, lest the user die of
old age before a move is made.

[OldMoses]

Vince's toggle method is neat, and new to me.  It
even works for flipping between 0 and 1.  But it
does incur 3 register loads and 2 register operations.

Vince does cool stuff, am I right that the "TRUE" / "FALSE" is a example of "branchless" programming?