Homework 4

CAP 314

Principles of Software Engineering

SUBMITTED TO- Deepak Sir

SUBMITTED BY- SACHIN RAJ

B34 D3901

PART A

Q.1. Apply a "stepwise refinement approach" to develop three different levels of procedural abstraction for one or more of the following programs: a. Develop a check writer that, given a numeric dollar amount, will print the amount

in words normally required on a check. b. Iteratively solve for the roots of a transcendental equation.c. Develop a simple round-robin scheduling algorithm for an operating system.Ans-

Refinement 1:write dollar amount in wordsRefinement 2:procedure write_amount;validate amount is within bounds;parse to determine each dollar unit;generate alpha representation;end write_amountRefinement 3:procedure write_amount;do while checks remain to be printedif dollar amount > upper amount boundthen print "amount too large errormessage;else set process flag true;endif;determine maximum significant digit;do while (process flag true andsignificant digits remain)set for corresponded alpha phrase;divide to determine whole numbervalue;concatenate partial alpha string;reduce significant digit count byone;enddoprint alpha string;enddoend write_amount

Q.2. Discuss the relationship between the concept of information hiding as an attribute of effective modularity and the concept of module independence.Ans-Information hiding can be related to both coupling and cohesion concepts. By limiting the availability of information to only those modules that have absolute need, coupling between modules is inherently reduced. In general, isolation of information predicates isolation of function; therefore, cohesion of individual modules can also beimproved.Information hiding as an attribute of effective modularityInformation Hiding implies that effective modularity can be achieved by defining a set of independent modules that communicate with one another only that information necessary to achieve software function. Abstraction helps to define the procedural (or informational) entities that make up the software.

The use of information hiding as a design criterion for modular systems provides the greatest benefits when modifications are required during testing and later, during software maintenance. concept of module independenceThe concept of Module independence is a direct outgrowth of modularity and the concepts of abstraction and information hiding.Functional independence is achieved by developing modules with single-minded function and an aversion to excessive interaction with other modules. Independent modules are easier to maintain (and test) because secondary effects caused by design or code modification are limited, error propagation is reduced, and reusable modules are possible.

Q.3. Develop two additional design principles that “reduce the user’s memory load.”Ans-If the user desires, display shortcut command sequences on the screen at all times. Provide the facilities for "hints" when a WebApp requires passwordinput.Other Also Can Be Possible Reduce demand on short-term memory. Provide

visual cues that enable a user to recognize past actions, rather than having to recall them.It means we have provide easy interface to customer that will help to customer easily.and we also need to provide simple functionality(simple module coding,array)etc.

Establish meaningful defaults. A user should be able to specify individual preferences; however, a reset option should be available to enable the redefinition of original default values.Define shortcuts that are intuitive.

If i am creating a software then we must need to use shortcuts keys,that helps to customer remember. This is the best way to “reduce the user’s memory load.”

PART B

Q.4. All modern programming languages implement the structured programming constructs. Provide examples from three programming languages.Ans-C language structured programming constructsC is an imperative (procedural) systems implementation language. It was designed to be compiled using a relatively straightforward compiler, to provide low-level access to memory, to provide language constructs that map efficiently to machine instructions, and to require minimal run-time support. C was therefore useful for many applications that had formerly been coded in assembly language.Java structured programming constructsJava applications are typically compiled to bytecode (class file) that can run on any Java Virtual Machine (JVM) regardless of computer architecture. Java is a general-purpose, concurrent, class-based, object-oriented language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere". Java is currently one of the most popular programming languages in use, and is widely used from application software to web applications. Pascal structured programming constructsPascal, in its original form, is a purely procedural language and includes the traditional array of ALGOL-like control structures with reserved words such as if, then, else,

while, for, and so on. However, Pascal also has many data structuring facilities and other abstractions which were not included in the original ALGOL 60, like type definitions, records, pointers, enumerations, and sets.

Q.5. A program reads three integer values. The three values are interpreted as representing the lengths of the sides of a triangle. The program prints a message that states whether the triangle is scalene, isosceles, or equilateral. Develop a set of test cases that you feel will adequately test this program.Ans-In a valid triangle, no side may have a length of zero or less, and each side must be shorter than the sum of all sides divided by 2.Equilateral triangle: all sides are of equal length. Isosceles triangle: two sides are of equal length. Scalene triangle: all sides are of unequal length.

Q.6. If you could select only three test case design methods to apply during unit testing, what would they be and why?Ans-If only three test case design methods could be selected during unit test they would be:1. Basis path testing—it's critically important to ensure that all statements in the program have been exercised.2. Equivalence partitioning—an effective blackbox test at the module level.3. Boundary value analysis—"bugs lurk in corners and congregate at boundaries.”Naturally, good arguments can be made for other combinations of test case design techniques.