Truth table: Difference between revisions
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* [http://www.google.co.uk/search?q=truth+table&hl=en&client=firefox-a&hs=Om7&rls=org.mozilla:en-GB:official&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=C0uuTtjuH4Wt8gOF4dmYCw&ved=0CDUQsAQ&biw=941&bih=931&sei=%20Jk-uTuKKD4Sg8QOFkPGcCw some "truth table" examples from Google]. |
* [http://www.google.co.uk/search?q=truth+table&hl=en&client=firefox-a&hs=Om7&rls=org.mozilla:en-GB:official&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=C0uuTtjuH4Wt8gOF4dmYCw&ved=0CDUQsAQ&biw=941&bih=931&sei=%20Jk-uTuKKD4Sg8QOFkPGcCw some "truth table" examples from Google]. |
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<br><br> |
<br><br> |
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=={{header|ALGOL 68}}== |
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{{works with|ALGOL 68G|Any - tested with release 2.8.3.win32}} |
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Uses the Algol 68G specific evaluate procedure to evaluate the Boolean expressions. The expressions must therefore be infix and valid Algol 68 boolean expressions. |
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<lang algol68># prints the truth table of a boolean expression composed of the 26 lowercase variables a..z, # |
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# the boolean operators AND, OR, XOR and NOT and the literal values TRUE and FALSE # |
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# The evaluation is done with the Algol 68G evaluate function which is an extension # |
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PROC print truth table = ( STRING expr )VOID: |
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BEGIN |
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# recursively prints the truth table # |
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PROC print line = ( INT v )VOID: |
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IF v > UPB bv |
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THEN |
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# at the end of the variables - print the line # |
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FOR e TO UPB bv DO |
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IF used[ e ] THEN print( ( " ", bv[ e ], " " ) ) FI |
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OD; |
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print( ( " ", evaluate( expr ), newline ) ) |
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ELIF used[ v ] |
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THEN |
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# have another variable # |
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bv[ v ] := TRUE; |
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print line( v + 1 ); |
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bv[ v ] := FALSE; |
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print line( v + 1 ) |
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ELSE |
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# this variable is not used # |
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print line( v + 1 ) |
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FI # print line # ; |
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# returns the name of the variable number # |
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PROC variable name = ( INT number )CHAR: REPR ( number + ( ABS "a" - 1 ) ); |
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# the 26 boolean variables # |
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BOOL a := FALSE, b := FALSE, c := FALSE, d := FALSE, e := FALSE, f := FALSE; |
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BOOL g := FALSE, h := FALSE, i := FALSE, j := FALSE, k := FALSE, l := FALSE; |
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BOOL m := FALSE, n := FALSE, o := FALSE, p := FALSE, q := FALSE, r := FALSE; |
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BOOL s := FALSE, t := FALSE, u := FALSE, v := FALSE, w := FALSE, x := FALSE; |
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BOOL y := FALSE, z := FALSE; |
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# table of the variables allowng access by number # |
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[]REF BOOL bv = ( a, b, c, d, e, f, g, h, i, j, k, l, m |
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, n, o, p, q, r, s, t, u, v, w, x, y, z |
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); |
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[ 26 ]BOOL used; |
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BOOL at least one variable := FALSE; |
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# determine which variables are used in the expression # |
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FOR v TO UPB bv DO |
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used[ v ] := char in string( variable name( v ), NIL, expr ); |
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IF used[ v ]THEN at least one variable := TRUE FI |
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OD; |
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# print truth table headings # |
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print( ( expr, ":", newline ) ); |
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FOR v TO UPB bv DO |
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IF used[ v ] THEN print( ( " ", variable name( v ), " " ) ) FI |
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OD; |
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print( ( " value", newline ) ); |
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FOR v TO UPB bv DO |
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IF used[ v ] THEN print( ( " - " ) ) FI |
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OD; |
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print( ( " -----", newline ) ); |
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# evaluate the expression for each cobination of variables # |
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IF at least one variable |
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THEN |
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# the expression does not consist of literals only # |
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FOR v TO UPB bv DO bv[ v ] := FALSE OD; |
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print line( LWB bv ) |
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ELSE |
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# the expression is constant # |
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print( ( " ", evaluate( expr ), newline ) ) |
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FI |
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END # print truth table # ; |
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# print truth tables from the user's expressions # |
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print( ( "Please enter Boolean expressions using variables a, b, c, ..., z,", newline ) ); |
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print( ( "operators AND, OR, NOT and XOR and literals TRUE and FALSE", newline ) ); |
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print( ( "(Note operators and TRUE/FALSE must be uppercase and variables must be lower case)", newline ) ); |
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print( ( "Enter a blank line to quit", newline ) ); |
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WHILE |
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STRING expr; |
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print( ( "expression> " ) ); |
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read( ( expr, newline ) ); |
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expr /= "" |
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DO |
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print truth table( expr ) |
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OD</lang> |
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{{out}} |
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<pre> |
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Please enter Boolean expressions using variables a, b, c, ..., z, |
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operators AND, OR, NOT and XOR and literals TRUE and FALSE |
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(Note operators and TRUE/FALSE must be uppercase and variables must be lower case) |
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Enter a blank line to quit |
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expression> a OR b |
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a OR b: |
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a b value |
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- - ----- |
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T T T |
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T F T |
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F T T |
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F F F |
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expression> a AND ( b OR f ) |
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a AND ( b OR f ): |
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a b f value |
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- - - ----- |
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T T T T |
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T T F T |
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T F T T |
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T F F F |
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F T T F |
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F T F F |
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F F T F |
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F F F F |
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expression> ( NOT a ) OR ( b AND c ) |
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( NOT a ) OR ( b AND c ): |
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a b c value |
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- - - ----- |
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T T T T |
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T T F F |
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T F T F |
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T F F F |
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F T T T |
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F T F T |
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F F T T |
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F F F T |
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expression> |
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</pre> |
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=={{header|D}}== |
=={{header|D}}== |
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