LAB 2 INTRODUCTION TO PROGRAMMING

Transcription

1 LAB 2 INTRODUCTION TO PROGRAMMING School of Computer and Communication Engineering Universiti Malaysia Perlis 1

2 OBJECTIVES 1. Clear understanding of sequential, selection and repetition structure to solve programming problem. [Jelas mengenai struktur turutan, pilihan dan gelung untuk menyelesaikan masalah pemprograman.] 2. Able to implement single or combination of the mentioned structures in programming problem solving. [Berupaya menggunakan satu atau kombinasi struktur yang telah dinyatakan di dalam menyelesaikan masalah pemprograman.] NOTES 1. Programming problem can be solved using an algorithm. An algorithm is a method to solve computing problem involving executions of series of actions in specific order. 2. Algorithm can be represented in pseudocode and/or flowchart. 3. Pseudocode is artificial and informal language that helps programmers develop algorithms. For example: if student s mark is greater than or equal to 50 Print Pass else Print Fail 4. Flowchart is a visual form of an algorithm. For example: marks>=50 Print pass Print fail 2

3 5. These are basic symbols in a flowchart. The oval shape denotes the starting or ending of a program. The rectangular shape denotes process that is to be performed. The process can be calculation of a formula or initialization of a value. The skewed rectangular can denote reading input or displaying output. The diamond shape takes up a variable and perform comparison. The result of the comparison is a decision which can be true or false. The arrow shows the flow or direction of actions in an algorithm. The circle shape denotes as a connector to subsequent actions. 6. During problem analysis, programmers have to decide the structure to be used in order to solve the programming problems. The structure can be a simple sequential structure and/or combinations of selection or repetition structures. 7. Sequential structure is a series of steps executed sequentially by default. For example: A program that calculates and prints the sum of two integers A and B. 3

4 8. Selection structure choose or select among alternative courses of actions. For example: A program prints pass if marks entered by user is greater or equal than 50. Otherwise it prints fail. 1. Flowchart Pseudocode 1. Start Start 2. Read mark 3. If mark is greater or equal than 50 Read mark 3.1 print pass else 3.2 print fail 4. End True mark>=50 Print pass False Print fail 4 End

5 9. Repetition structure specifies a block of one or more statements that are repeatedly executed until a condition is satisfied. For example: A program calculates and prints sum of numbers from 1 to 5. Pseudocode 1. Start 2. Initialize counter to 1 and sum to 0 3. While counter is less than 5 a. Calculate sum b. Update counter 4. Print sum 5. End Flowchart Start Initialize counter = 1, sum = 0 False counter <=5 True Calculate sum = sum + counter Update counter by 1 Print sum End 5

6 LAB EXERCISE Produce either a flowchart or pseudocode to these given problems. 1. Your Mathematics lecturer asks you to write a program in C to calculate excess volume of cylinders. The excessive volume is described in the figure given below whereby it is calculated by subtracting bigger cylinder volume with smaller cylinder volume. Given formula to calculate volume of a cylinder: Volume of a cylinder = π * radius * radius * height rbig hsmall hbig rsmall Sample output is given below. This program calculates excess volume of cylinders Enter bigger cylinder radius and height : 4 5 Enter smaller cylinder radius and height : 2 3 Volume bigger cylinder : Volume smaller cylinder : Excess volume : a) Identify how many and what is/are the input and output b) Identify what is to be calculated 6

7 2. A program tasks are to find the equivalent series and parallel resistance for 3 resistor values. Your program should read the 3 resistor values and then compute the equivalent series and parallel resistance for all 3 resistors. For example, if the 3 resistor values are r1=100, r2=200 and r3=300 ohms, respectively, their equivalent series resistance is r1 + r2 + r3 = = 600 ohms and their equivalent parallel resistance = 1 / [1/r1 + 1/r2 + 1/r3] = 1/[ ] = ohms. a) Identify how many and what is/are the input and output b) Identify what is to be calculated 7

8 3. Produce a C program that takes the x-y coordinates of a point in the Cartesian plane illustrated in figure below and displays a message telling either an axis on which the point lies or the quadrant in which it is found. y QI QIII QI QIV Q x Sample lines of output: (-1.0, -2.5) is in quadrant III (0.0, 4.8) is on the y axis a) Identify how many and what is/are the input and output b) Identify what variable that is used to perform comparison c) Is there any calculation involved? 8

9 4. A program identify whether a letter that is entered is a vowel or consonant. a) Identify how many and what is/are the input and output b) Identify what variable that is used to perform comparison c) Is there any calculation involved? 9

10 5. A program containing a loop to display a) Identify how many and what is/are the input and output. Think! Should I need input to display this patterns? b) Identify what variable that is used to perform comparison so that you can perform repetition c) Is there any calculation involved? 10

11 6. A program read marks for 10 students. If marks is greater than 50, student passes else they fail. Count how many students pass and fail and, print the result. a) Identify how many and what is/are the input and output. b) Identify what variable that is used to perform comparison so that you can perform selection and/or repetition c) Is there any calculation involved? 11

12 7. A program mimics a calculator. The program should take as input two integers and the operation to be performed. It should then output the numbers, the operator, and the result. (For division, if the denominator is zero, output an appropriate message.) Some sample outputs as follow : Please enter 2 integers: 4 2 Please enter an operator (+, -, *,/): * Result : 8 Do you want to continue : y or n?y Please enter 2 integers: 2 0 Please enter an operator (+, -, *,/): / ERROR denominator is zero!cannot divide by zero Do you want to continue : y or n?n 12

13 8. Construction engineers use concrete to build high-rise buildings. Since concrete nearly is incapable of resisting tension loads, reinforcing steel, known as rebar, is embedded in concrete to resist tension. The bar is available in a number of sizes. Table 1 shows the ASTM (American Society for Testing and Materials) standard reinforcing bars size, weight, and diameter: Table 1 Size Weight (lb./ft.) Diameter (in.) Write a C program to calculate the total weight of the rebar for 5 sets of data by input value of rebar size and length. Formula: Total Weight = Length* Weight Tips: Use selection to differentiate the size of rebar and loop to repeat the process.. Sample Output: Program to Calculate the Total Weight of the Rebar. Please Enter Size (2,3,4,5 or 6) and Length of Rebar: Rebar Size 4, Diameter inches and Length ft Total Weight lb Please Enter Size (2,3,4,5 or 6) and Length of Rebar: Rebar Size 2, Diameter inches and Length ft Total Weight lb : Please Enter Size (2,3,4,5 or 6) and Length of Rebar: Rebar Size 2, Diameter inches and Length ft Total Weight lb 13