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Chapter-01

Introduction to Software Engineering

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Software Engineering

Procedural Design

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Problem Solving

• Does anyone carpet?

• Let’s solve this area problem:– Write a program that, given a length and width,

computes the area of a carpet.

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Behavior

A. Describe the desired behavior of the program:Our program should display a prompt for length and

width, read length and width from the keyboard, compute the corresponding area, and display the area, along with a descriptive label on the screen.

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Data

B. Identify the data in the behavioral description (other than program and user):Our program should display a prompt for length and

width on the screen, read length and width from the keyboard, compute the corresponding area, and display the area, along with a descriptive label on the screen.

These make up the data in our program.

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Operations: Functions or Procedures

C. Identify the verbs in the behavioral description:Our program should display a prompt for the length and

width on the screen, read the length and width from the keyboard, compute the corresponding area, and display the area, along with a descriptive label on the screen.

These make up the operations in our program.

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Algorithm

D. Organize data and operations into a sequenceof steps that solves the problem,called an algorithm.

1. Display a prompt for length and width on the screen.

Function call printf()

2. Read length and width from the keyboard.

Function call scanf()

3. Compute area from length and width .

4. Display area , plus an informative label on the screen.

Function call printf()

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Coding

Once we have designed an algorithm, the next step is to translate that algorithm into a high level language like C++.

This involves figuring out how to – represent our data, and– perform our operations,

in C++ (with the aid of a book...)

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Representing data

A. Determine a type and name for each data item:

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Performing Operations

B. Identify the C++ operator to perform a given operation, if there is one...

Operation Library? Name

Display a stringRead an intRead an intCompute areaDisplay an int

stdiostdiostdio--stdio

printf()scanf()scanf ()--printf()

To compute area, we need to find the area-length-width formula in a geometry book...

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Length and Width-to-Area

In a geometry book, we find that– area is the product of length and width

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Operations (Revised)

Operation Library? Name

Display a stringRead an intRead an intCompute pressure

Multiply two integers

Display an int

stdiostdiostdio--

built-in

stdio

printf()scanf()scanf()--*

printf()

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Documentation

Always begin a file with an opening comment:

/* area.cpp is a area calculating utility. * Author: Bazlur Rasheed * Date: 02 July 2000 * Purpose: Calculate area of a rectangle. */

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Coding: Program Stub

/* area.cpp is a area calculating utility. * ... */

#include <stdio.h> // printf(), scanf()

int main(){}

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Coding: Algorithm Steps 1

// ...int main(){printf(“\n Rectangular Area Calculator!!”);printf("\n Enter the length (meter) and ”); printf(“width (meter)”);printf("\n seperated by a space and “);printf(” followed by the enter key: ";);

}

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Coding: Algorithm Steps 2

// ...int main(){printf(“\n Rectangular Area Calculator!!”);printf("\n Enter the length (meter) and ”); printf(“width (meter)”);printf("\n seperated by a space and “);printf(” followed by the enter key: ";);int length, width;scanf(“%d %d”, &length, &width);

}

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Coding: Algorithm Step 3// ... printf(“\n Rectangular Area Calculator!!”);printf("\n Enter the length (meter) and ”); printf(“width (meter)”);printf("\n seperated by a space and “);printf(” followed by the enter key: ";);int length, width;scanf(“%d %d”, &length, &width);

int area = length * width;}

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Coding: Algorithm Step 4

// ... int area = length * width;

printf("\n The area is %d”, area);printf(” square meter. \n\n”);

}

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TestingRun your program using sample data

(whose correctness is easy to check):

Rectangular Area Calculator! Enter the length (meter) and width (meter) separated by a space and followed by the enter key: 10 20

The area is 200 square meter

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Summary of Procedural

Procedural is a methodology for designing programs:

1. Describe the desired behavior of the program.

2. Identify the data required.

3. Identify the operations (functions) required.

4. Organize data and operations into an algorithm, refining data and operation lists as necessary.

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Summary of Procedural Programming

Writing a program consists of these steps:1. Design an algorithm for your program.

2. Code your design.

3. Test your program.

4. Maintain/upgrade your program as necessary.