CAD in Civil Engineering - Baustatik-Info-Server

Page 26 Computer Languages for Engineering - SS 13Operator CommentExample< less than x = 23 < 13 >>> .false.> .true.> greater x = 23 > 13 >>> .true.>= left shift of bits x = 23 >= 23 >>> .true.== equal x = 23 == 23 >>> .true./= non equal x = 23 /= 23 >>> .false.The result of a boolean expression like above are the boolean values .false. or .true.. To combinecomparing expressions the following logical operators can be used. 67Operator Comment Example.and. logical and x = 1 .lt. 2 .and. 2 .lt. 3 >>> .true..or. logical or x = 1 .lt. 2 .or. 2 .gr. 3 >>> .true..equ. logical or x = .true. >>> y = .false. >>> x .eqv. y >>> .false..nequ. logical or x = .true. >>> y = .false. >>> x .neqv. y >>> .true..not. logical not x = .not. (1 .lt. 2) >>> .false.The truth table for the AND operator ∧ is given as follows..true. ∧ .true. = .true. (2.1).true. ∧ .false. = .false..false. ∧ .true. = .false..false. ∧ .false. = .false.The truth table for the OR operator ∨ is given as follows..true. ∨ .true. = .true. (2.2).true. ∨ .false. = .true..false. ∨ .true. = .true..false. ∨ .false. = .false.2.7 File IO, Screen and KeyboardTo communicate with the program the two statements read and write are necessary. In the most simplecase we read the input data from the keyboard and write the output data into a console window. A simpleoutput gives us the example helloworld, see section 2.2.6 To make expressions clear parenthesis should be used. A term within a parenthesis is evaluated first and it’s result then isused in further evaluations outside the parenthesis. With parenthesis the order of the evaluation can be set.7 The logical operator .NEQV. implements the exclusive OR.E. Baeck