B

Task/Boolean-values/0DESCRIPTION

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+Show how to represent the boolean states "true" and "false" in a language. If other objects represent "true" or "false" in conditionals, note it.
+
+;Cf.
+* [[Logical operations]]

Task/Boolean-values/1META.yaml

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+---
+note: Basic language learning

Task/Boolean-values/ALGOL-68/boolean-values.alg

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+BOOL f = FALSE, t = TRUE;
+[]BOOL ft = (f, t);
+STRING or = " or ";
+FOR key TO UPB ft DO
+  BOOL val = ft[key];
+  UNION(VOID, INT) void = (val|666|EMPTY);
+  REF STRING ref = (val|HEAP STRING|NIL);
+  INT int = ABS val;
+  REAL real = ABS val;
+  COMPL compl = ABS val;
+  BITS bits = BIN ABS val; # or bitspack(val); #
+  BYTES bytes = bytes pack((val|"?"|null char)*bytes width);
+  CHAR char = (val|"?"|null char);
+  STRING string = (val|"?"|"");
+
+  print((((val | "TRUE" | "FALSE" ), ": ", val, or, (val|flip|flop), new line)));
+  print(("  void: ", " => ", (void|(VOID):FALSE|TRUE), new line));
+  print(("   ref: ", " => ", ref ISNT REF STRING(NIL), new line));
+  print(("   int: ", int     , " => ", int /= 0, new line));
+  print(("  real: ", real    , " => ", real /= 0, new line));
+  print((" compl: ", compl   , " => ", compl /= 0, new line));
+  print(("  bits: ", bits    , " => ", ABS bits /= 0, or, bits /= 2r0, or,
+                     bits width ELEM bits, or, []BOOL(bits)[bits width], new line));
+  print((" bytes: """, STRING(bytes)    , """ => ", 1 ELEM bytes /= null char, or,
+                       STRING(bytes) /= null char*bytes width, or,
+                       STRING(bytes)[1] /= null char, new line));
+  print(("  char: """, char  , """ => ", ABS char /= 0 , or, char /= null char, new line));
+  print(("string: """, string  , """ => ", string /= "", or, UPB string /= 0, new line));
+  print((new line))
+OD

Task/Boolean-values/AWK/boolean-values.awk

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+BEGIN {
+   # Do not put quotes round the numeric values, or the tests will fail
+   a = 1    # True
+   b = 0    # False
+
+   # Boolean evaluations
+   if (a) { print "first test a is true" }        # This should print
+   if (b) { print "second test b is true" }       # This should not print
+   if (!a) { print "third test a is false" }      # This should not print
+   if (!b) { print "forth test b is false" }      # This should print
+
+   # Boolean evaluation using comparison against zero
+   if (a == 0) { print "fifth test a is false" }  # This should not print
+   if (b == 0) { print "sixth test b is false" }  # This should print
+   if (a != 0) { print "seventh test a is true" } # This should print
+   if (b != 0) { print "eighth test b is true" }  # This should not print
+
+ }

Task/Boolean-values/Ada/boolean-values.ada

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+   type Boolean is (False, True);

Task/Boolean-values/BASIC/boolean-values.bas

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+10 LET A%=0
+20 LET B%=NOT(A%)
+30 PRINT "THIS VERSION OF BASIC USES"
+40 PRINT B%; " AS ITS TRUE VALUE"
+50 IF A% THEN PRINT "TEST ONE DOES NOT PRINT"
+60 IF B% THEN PRINT "TEST TWO DOES PRINT"
+70 IF A%=0 THEN PRINT "TEST THREE (FALSE BY COMPARISON) DOES PRINT"
+80 IF B%=0 THEN PRINT "TEST FOUR (FALSE BY COMPARISON) DOES NOT PRINT"
+90 IF A%<>0 THEN PRINT "TEST FIVE (TRUE BY COMPARISON) DOES NOT PRINT"
+100 IF B%<>0 THEN PRINT "TEST SIX (TRUE BY COMPARISON) DOES PRINT"
+110 END

Task/Boolean-values/BASIC256/boolean-values.basic256

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+' BASIC256 used numbers to represent true and false
+' values.  Zero is false and anything else is true.
+' The built in constants true and false exist
+' and represent one and zero respectively.
+
+print false
+print true

Task/Boolean-values/BBC-BASIC/boolean-values.bbc

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+      REM BBC BASIC uses integers to represent Booleans; the keywords
+      REM FALSE and TRUE equate to 0 and -1 (&FFFFFFFF) respectively:
+
+      PRINT FALSE
+      PRINT TRUE

Task/Boolean-values/CoffeeScript/boolean-values.coffee

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+h1 = {foo: "bar"}
+h2 = {foo: "bar"}
+
+true_expressions = [
+  true
+  1
+  h1? # because h1 is defined above
+  not false
+  !false
+  []
+  {}
+  1 + 1 == 2
+  1 == 1 # simple value equality
+  true or false
+]
+
+false_expressions = [
+  false
+  not true
+  undeclared_variable?
+  0
+  ''
+  null
+  undefined
+  h1 == h2 # despite having same key/values
+  1 == "1" # different types
+  false and true
+]

Task/Boolean-values/Erlang/boolean-values.erl

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+1> 1 < 2.
+true
+2> 1 < 1.
+false
+3> 0 == false.
+false

Task/Boolean-values/Forth/boolean-values.fth

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+TRUE .    \ -1
+FALSE .   \ 0

Task/Boolean-values/Haskell/boolean-values.hs

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+data Bool = False | True    deriving (Eq, Ord, Enum, Read, Show, Bounded)

Task/Boolean-values/Lua/boolean-values.lua

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+if 0 then print "0" end             -- This prints
+if "" then print"empty string" end  -- This prints
+if {} then print"empty table" end   -- This prints
+if nil then print"this won't print" end
+if true then print"true" end
+if false then print"false" end      -- This does not print

Task/Boolean-values/MATLAB/boolean-values.m

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+>> islogical(true)
+
+ans =
+
+     1
+
+>> islogical(false)
+
+ans =
+
+     1
+
+>> islogical(logical(1))
+
+ans =
+
+     1
+
+>> islogical(logical(0))
+
+ans =
+
+     1
+
+>> islogical(1)
+
+ans =
+
+     0
+
+>> islogical(0)
+
+ans =
+
+     0

Task/Boolean-values/Perl/boolean-values-1.pl

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+my $x = 0.0;
+my $true_or_false = $x ? 'true' : 'false';     # false

Task/Boolean-values/Perl/boolean-values-2.pl

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+my $x = 1;          # true
+
+my $true_or_false;
+
+if ($x) {
+    $true_or_false = 'true';
+}
+else {
+    $true_or_false = 'false';
+}

Task/Boolean-values/Perl/boolean-values-3.pl

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+print (7 && 2);  # 2, rather than 1(true)
+print (2 && 7);  # 7, rather than 1(true)
+print (7 xor 2); # empty string, rather than 0(false)
+print ('apples' && 'pears');  # pears, rather than 1(true)
+print ('apples' xor 'pears'); # empty string, rather than 0(false)

Task/Boolean-values/Perl/boolean-values-4.pl

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+# This does not work
+# true and false are not special so will be treated as bareword strings
+if (true) { print "true is true\n" };            # This prints
+if (false) { print "false is true\n" };          # So does this
+if (spongebob) { print "spongebob is true\n" };  # A bareword string

Task/Boolean-values/Python/boolean-values.py

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+>>> True
+True
+>>> not True
+False
+>>> # As numbers
+>>> False + 0
+0
+>>> True + 0
+1
+>>> False + 0j
+0j
+>>> True * 3.141
+3.141
+>>> # Numbers as booleans
+>>> not 0
+True
+>>> not not 0
+False
+>>> not 1234
+False
+>>> bool(0.0)
+False
+>>> bool(0j)
+False
+>>> bool(1+2j)
+True
+>>> # Collections as booleans
+>>> bool([])
+False
+>>> bool([None])
+True
+>>> 'I contain something' if (None,) else 'I am empty'
+'I contain something'
+>>> bool({})
+False
+>>> bool("")
+False
+>>> bool("False")
+True

Task/Boolean-values/REXX/boolean-values-1.rexx

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+ true = 1
+false = 0

Task/Boolean-values/REXX/boolean-values-2.rexx

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+true  = (1=1)
+false = (1=0)

Task/Boolean-values/REXX/boolean-values-3.rexx

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+true  = (1==1)
+false = (1==0)

Task/Boolean-values/REXX/boolean-values-4.rexx

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+true  = (1==1)
+false = \true

Task/Boolean-values/REXX/boolean-values-5.rexx

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+false = ¬true

Task/Boolean-values/REXX/boolean-values-6.rexx

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+true  =            1984  =  1984
+false =           'war'  =  'peace'
+false =       'freedom'  =  'slavery'
+false =     'ignorance'  =  'strength'

Task/Boolean-values/Racket/boolean-values.rkt

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+(cond ([(< 4 3) 'apple]
+       ['bloggle 'pear]
+       [else 'nectarine])

Task/Boolean-values/SNUSP/boolean-values.snusp

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+$!/?\=false= + =true=#
+  \-/

Task/Boolean-values/Sather/boolean-values.sa

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+v:BOOL := true; -- ok
+i:INT := 1;
+v := 1; -- wrong
+if i then ... end; -- wrong: if requires a bool!
+-- BUT
+v := 1.bool; -- ok
+if i.bool then ... end; -- ok

Task/Boolean-values/Tcl/boolean-values-1.tcl

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+% if {""} then {puts true} else {puts false}
+expected boolean value but got ""

Task/Boolean-values/Tcl/boolean-values-2.tcl

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+if {[string is false -strict $string]} ...