dale roberts program control using java - boolean expressions dale roberts, lecturer computer...
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Dale Roberts
Program Control using JavaProgram Control using Java
- Boolean Expressions- Boolean Expressions
Dale Roberts, LecturerComputer Science, IUPUIE-mail: [email protected]
Department of Computer and Information Science,School of Science, IUPUI
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5.8 Logical Operators5.8 Logical Operators
Logical operatorsLogical operatorsAllows for forming more complex conditionsAllows for forming more complex conditions
Combines simple conditionsCombines simple conditions
Java logical operatorsJava logical operators&&&& (conditional AND) (conditional AND)
|||| (conditional OR) (conditional OR)
&& (boolean logical AND) (boolean logical AND)
|| (boolean logical inclusive OR) (boolean logical inclusive OR)
^̂ (boolean logical exclusive OR) (boolean logical exclusive OR)
!! (logical NOT) (logical NOT)
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5.8 Logical Operators (Cont.)5.8 Logical Operators (Cont.)
Conditional AND (Conditional AND (&&&&) Operator) OperatorConsider the following Consider the following ifif statement statementifif ( gender == ( gender == FEMALEFEMALE && age >= && age >= 6565 ) )
++seniorFemales;++seniorFemales;
Combined condition is Combined condition is truetrue if and only if both simple conditions are if and only if both simple conditions are truetrue
Combined condition is Combined condition is falsefalse if either or both of the simple conditions are if either or both of the simple conditions are falsefalse
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Fig. 5.14 Fig. 5.14 | | &&&& (conditional AND) operator truth table. (conditional AND) operator truth table.
expression1 expression2 expression1 && expression2 false false False false true False true false False true true True
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5.8 Logical Operators (Cont.)5.8 Logical Operators (Cont.)
Conditional OR (Conditional OR (||||) Operator) OperatorConsider the following Consider the following ifif statement statementifif ( ( semesterAverage >= ( ( semesterAverage >= 9090 ) || ( finalExam >= ) || ( finalExam >= 9090 ) )
System.out.println( “Student grade is A” );System.out.println( “Student grade is A” );
Combined condition is Combined condition is truetrue if either or both of the simple condition are if either or both of the simple condition are truetrue
Combined condition is Combined condition is falsefalse if both of the simple conditions are if both of the simple conditions are falsefalse
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Fig. 5.15 Fig. 5.15 | | |||| (conditional OR) operator truth table. (conditional OR) operator truth table.
expression1 expression2 expression1 || expression2 false false false false true true true false true true true true
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5.8 Logical Operators (Cont.)5.8 Logical Operators (Cont.)
Short-Circuit Evaluation of Complex ConditionsShort-Circuit Evaluation of Complex ConditionsParts of an expression containing Parts of an expression containing &&&& or or |||| operators are operators are evaluated only until it is known whether the condition is evaluated only until it is known whether the condition is true or falsetrue or false
E.g., E.g., ( gender == ( gender == FEMALEFEMALE ) && ( age >= ) && ( age >= 6565 ) )Stops immediately if gender is not equal to Stops immediately if gender is not equal to FEMALEFEMALE
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5.8 Logical Operators (Cont.)5.8 Logical Operators (Cont.)
Boolean Logical AND (Boolean Logical AND (&&) Operator) OperatorWorks identically to Works identically to &&&&
Except Except && always evaluate both operands always evaluate both operands
Boolean Logical OR (Boolean Logical OR (||) Operator ) Operator Works identidally to Works identidally to ||||
Except Except || always evaluate both operands always evaluate both operands
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5.8 Logical Operators (Cont.)5.8 Logical Operators (Cont.)
Boolean Logical Exclusive OR (Boolean Logical Exclusive OR (^̂))One of its operands is One of its operands is truetrue and the other is and the other is falsefalse
Evaluates to Evaluates to truetrue
Both operands are Both operands are truetrue or both are or both are falsefalseEvaluates to Evaluates to falsefalse
Logical Negation (Logical Negation (!!) Operator) OperatorUnary operatorUnary operator
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Fig. 5.16 Fig. 5.16 | | ^̂ (boolean logical exclusive OR) operator truth table. (boolean logical exclusive OR) operator truth table.
expression1 expression2 expression1 ^ expression2 false false false false true true true false true true true false
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Fig. 5.17 Fig. 5.17 ||! ! (logical negation, or logical NOT) operator truth (logical negation, or logical NOT) operator truth table.table.
expression !expression false true true false
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Fig. 5.19 Fig. 5.19 | Precedence/associativity of the operators discussed | Precedence/associativity of the operators discussed so far.so far.
Operators Associativity Type
++ -- right to left unary postfix ++ - + - ! (type) right to left unary prefix * / % left to right multiplicative + - left to right additive < <= > >= left to right relational == != left to right equality & left to right boolean logical AND ^ left to right boolean logical exclusive OR | left to right boolean logical inclusive OR && left to right conditional AND || left to right conditional OR ?: right to left conditional = += -= *= /= %= right to left assignment
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AcknowledgementsAcknowledgementsDeitel, Java How to Program