tailieunhanh - Software Engineering For Students: A Programming Approach Part 39

Software Engineering For Students: A Programming Approach Part 39. This fully revised version of Doug Bell's Software Engineering: A Programming Approach continues to use the successful formula of the previous editions. The author's approach is to present the main principles, techniques and tools used in software engineering, one by one, chapter by chapter. This book is a unique introduction to software engineering for all students of computer science and its related disciplines. It is also ideal for practitioners wishing to remain current with new developments in the area | 358 Chapter 29 Software metrics and quality assurance how much will this software cost how much effort will be needed to alter this software to meet changed needs. In this chapter we review various ways of applying metrics to software. The purposes of metrics in software engineering include predicting qualities of software that is about to be developed making judgments on the quality of a piece of software that has been developed monitoring and improving the software development process comparing and assessing different development approaches. In this chapter we first review metrics then look at the application of quality assurance. Basic metrics The simplest measure of software is its size. Two possible metrics are the size in bytes and the size in number of statements. The size in statements is often termed LOCs lines of code sometimes SLOCs source lines of code . The size in bytes obviously affects the main memory and disk space requirements and affects performance. The size measured in statements relates to development effort and maintenance costs. But a longer program does not necessarily take longer to develop than a shorter program because the complexity of the software also has an effect. A metric such as LOCs takes no account of complexity. We shall see shortly how complexity can be measured. There are different ways of interpreting even a simple metric like LOCs since it is possible to exclude or include comments data declaration statements and so on. Arguably blank lines are not included in the count. The second major metric is person months a measure of developer effort. Since people s time is the major factor in software development person months usually determine cost. If an organization measures the development time for components the information can be used to predict the time of future developments. It can also be used to gauge the effectiveness of new techniques that are used. The third basic metric is the number of bugs. As a component is .