Arithmetic OperatorsArithmetic Operators in CDivisionDivision (con’t)Division By ZeroModulusUses for ModulusArithmetic Operators Rules of Operator PrecedenceUsing ParenthesesPractice With Evaluating ExpressionsA Sample ProjectThe Box - PseudocodeThe Box - Pseudocode (con’t)Slide 14Slide 15Slide 16Good Programming PracticeSlide 18Using the Incremental ApproachArithmetic OperatorsTopicsArithmetic OperatorsOperator PrecedenceEvaluating Arithmetic ExpressionsIn-class ProjectIncremental ProgrammingReadingSection 2.5Arithmetic Operators in C Name Operator ExampleAddition + num1 + num2Subtraction - initial - spentMultiplication * fathoms * 6Division / sum / countModulus % m % nDivisionIf both operands of a division expression are integers, you will get an integer answer. The fractional portion is thrown away.Examples : 17 / 5 = 3 4 / 3 = 1 35 / 9 = 3Division (con’t)Division where at least one operand is a floating point number will produce a floating point answer.Examples : 17.0 / 5 = 3.4 4 / 3.2 = 1.25 35.2 / 9.1 = 3.86813What happens? The integer operand is temporarily converted to a floating point, then the division is performed.Division By ZeroDivision by zero is mathematically undefined.If you allow division by zero in a program, it will cause a fatal error. Your program will terminate execution and give an error message.Non-fatal errors do not cause program termination, just produce incorrect results.ModulusThe expression m % n yields the integer remainder after m is divided by n.Modulus is an integer operation -- both operands MUST be integers.Examples : 17 % 5 = 2 6 % 3 = 0 9 % 2 = 1 5 % 8 = 5Used to determine if an integer value is even or odd 5 % 2 = 1 odd 4 % 2 = 0 evenIf you take the modulus by 2 of an integer, a result of 1 means the number is odd and a result of 0 means the number is even.The Euclid’s GCD Algorithm (done earlier) Uses for ModulusArithmetic Operators Rules of Operator PrecedenceOperator(s) Precedence & Associativity( )Evaluated first. If nested (embedded), innermost first. If on same level, left to right.* / % Evaluated second. If there are several, evaluated left to right+ -Evaluated third. If there are several, evaluated left to right.=Evaluated last, right to left.Using ParenthesesUse parentheses to change the order in which an expression is evaluated.a + b * c Would multiply b * c first, then add a to the result.If you really want the sum of a and b to be multiplied by c, use parentheses to force the evaluation to be done in the order you want.(a + b) * cAlso use parentheses to clarify a complex expression.Practice With Evaluating ExpressionsGiven integer variables a, b, c, d, and e, where a = 1, b = 2, c = 3, d = 4,evaluate the following expressions: a + b - c + d a * b / c 1 + a * b % c a + d % b - c e = b = d + c / b - aLet’s write a program that computes and displays the volume and surface area of a cube. Procedure:Use the pseudocode that we developed in “Algorithms, Part 3 of 3”Convert the algorithm to codeClean up the code (spacing, indentation, commenting)A Sample ProjectThe Box - PseudocodeDisplay “Enter the height: “Read <height>While (<height> <= 0 ) Display “The height must be > 0” Display “Enter the height: “ Read <height>End_whileThe Box - Pseudocode (con’t)Display “Enter the width: “Read <width>While (<width> <= 0 ) Display “The width must be > 0” Display “Enter the width: “ Read <width>End_whileThe Box - Pseudocode (con’t)Display “Enter the depth: “Read <depth>While (<depth> <= 0 ) Display “The depth must be > 0” Display “Enter the depth: “ Read <depth>End_whileThe Box - Pseudocode (con’t)<volume> = <height> X <width> X <depth><surface1> = <height> X <width><surface2> = <width> X <depth><surface3> = <height> X <depth><surface area> = 2 X (<surface1> + <surface2> + <surface3>)The Box - Pseudocode (con’t)Display “Height = “, <height>Display “Width = “, <width>Display “Depth = “, <depth>Display “Volume = “, <volume>Display “Surface Area = “, <surface area>Good Programming PracticeIt is best not to take the “big bang” approach to coding.Use an incremental approach by writing your code in incomplete, yet working, pieces.For example, for your projects,Don’t write the whole program at once.Just write enough to display the user prompt on the screen.Get that part working first (compile and run).Next, write the part that gets the value from the user, and then just print it out.Always have a working version of your program!Good Programming PracticeGet that working (compile and run). Next, change the code so that you use the value in a calculation and print out the answer.Get that working (compile and run). Continue this process until you have the final version.Get the final version working.Using the Incremental ApproachLet’s think about how we could have developed the volume and surface area program
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