ISBN : 978-81-963532-2-3 (E-Book) LOC is the simplest among all metrics available to estimate project size. This metric is verypopular because it is the simplest to use. Using this metric, the project size is estimated bycounting the number of source instructions in the developed program. Obviously, while countingthenumberofsourceinstructions,linesusedforcommentingthecodeandtheheaderlinesshould beignored. Determining the LOC count at the end of a project is a very simple job. However, accurateestimationoftheLOCcountatthebeginningofaprojectisverydifficult.Inordertoestimatethe LOC count at the beginning of a project, project managers usually divide the problem intomodules, and each module into submodules and so on, until the sizes of the different leaflevelmodules can be approximately predicted. To be able to do this, past experience in developingsimilarproductsishelpful.Byusingtheestimationofthelowestlevelmodules,projectmanag ers arriveat thetotal sizeestimation. Functionpoint(FP) Function point metric was proposed by Albrecht [1983]. This metric overcomes many of theshortcomings of the LOC metric. Since its inception in late 1970s, function point metric has beenslowly gaining popularity. One of the important advantages of using the function point metric isthat it can be used to easily estimate the size of a software product directly from the problemspecification. This is in contrast to the LOC metric, where the size can be accurately determinedonly after the product has fully been developed. The conceptual idea behind the function pointmetric is that the size of a software product is directly dependent on the number of differentfunctions or features it supports. A software product supporting many features would certainly beoflargersizethanaproductwithlessnumberoffeatures.Eachfunctionwheninvokedreads some input data and transforms it to the corresponding output data. For example, the issue bookfeature (as shown in fig. 31.1) of a Library Automation Software takes the name of the book asinput and displays its location and the number of copies available. Thus, a computation of thenumber of input and the output data values to a system gives some indication of the number offunctions supported by the system. Albrecht postulated that in addition to the number of basicfunctions that a software performs, the size is also dependent on the number of files and thenumberof interfaces. 148 Software Engineering Keerthana P, Manasa KN, Ganga D Bengal
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