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Operators in C programming : Logical operators

Operator                    Meaning
&&                              And
||                                    Or
!                                    Not
Logical operators are used to compare & evaluate logical and relational expressions. Operator && is referred as logic and, the operator || is referred as logic or. The result of a logic and operation will be true only if both operands are true where as the result of a logic or operation will be true if either operand is true or if both operands are true. In other word, the result of a logic or operation will be false only if both operands are false.

 Suppose that i is an integer variable whose value is 7, f is a floating-point variable whose value is 5.5 and c is a character variable that represents the character ‘w’. Several complex logical expressions that make use of these variables are shown below:
Expression                             Interpretation                        Value
(i>=6) && (c= = ‘w’)             true                                          1
(i>=6) || (c = = 119)                true                                          1
(f<11) && (i>100)                  false                                         0
(c! = ‘p’) || (iff<=10)               true                                          1
!(i>(f+1))                                 false                                         0

C also includes the unary operator ! that negates the value of a logical expression, i.e. it causes an expression that is originally true to become false and vice-versa. This operator is referred to as the logical negative (or logical not) operator.

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