# Maximum value float 32 bits 14 e 45 34 e38 8 variable

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Maximum Value float 32 bits +/- 1.4 E-45 +/- 3.4 E+38 8 Variable identifiers long dollarsOwnedByBillGates ; double percentagePassing101, percentagePassing105 ; int numberOfStudents ; boolean isTheLectureOverYet ; Examples • use sensible names that inform the programmer what the variable is used for. • all other letters should be lower case, • any subsequent words should start with a capital letter • all variable identifiers should begin with a lower case letter, Use the following style guidelines for ALL variable identifiers: 9 Assignment statements The assignment operator, = , is used to put a value into a variable e.g. X 37 x = 37; x = 37; int x; Assigns a value to the variable, i.e. puts the value into the box identified by the variable name. Both the variable and the value must be compatible types. The variable can only hold one value at a time – assigning a new value to a variable will replace any previous value. = 10 Declare and initialise a variable We can assign a value to a variable at the same time that we declare it. X 3 int x = 3; So instead of: we can simply have: x = 3; int x; 11 23 Printing variables A variable can be used anywhere that a literal can be used. 23 number System.out.println(number ); System.out.println( number ); int number = 23; will print out the value 23. We can print out the value stored in a variable using the System.out.println() statement, e.g. 12 Symbolic constants – final A symbolic constant is like a variable, except that the value it stores cannot change once it is initialised. A constant has to be initialised when it is defined. int DAYS_IN_YEAR = 365; Use the following style guidelines for naming symbolic constants: double GST_RATE = 0.125; • separate multiple words with an underscore For example • use all upper case letters

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CS101 Lecture 4 3 13 Expressions An expression is code that can be evaluated to give a single value: 35 Examples of Expressions a variable is an expression • a literal value is an expression Assume the variables age, number and value have been declared and initialised.
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• Summer '12
• Computer Science, Natural number, public void, public class

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