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Lines of Code (LOC)

Lines of Code (LOC) is a direct approach method and requires a higher level of detail by means of decomposition and partitioning. In contrast, Function Points (FP) is indirect an approach method where instead of focusing on the function it focuses on the domain characteristics (discussed later in the chapter).

From statement of software scope software is decomposed into problem functions that can each be estimated individually. LOC or FP (estimate variables) is then calculated for each function.

An expected value is then computed using the following formula.

where,

• EV stand for the estimation variable.
• Sopt stand for the optimistic estimate.
• Sm stands for the most likely estimate.
• Spess stand for the pessimistic estimate.

It is assumed that there is a very small probability that the actual size results will fall outside the optimistic or pessimistic value.

Once the expected value for estimation variable has been determined, historical LOC or FP data are applied and person months, costs etc are calculated using the following formula.

Productivity = KLOC / Person-month
Quality = Defects / KLOC
Cost = $ / LOC
Documentation = pages of documentation / KLOC

Where,

KLOC stand for no. of lines of code (in thousands).

Person-month stand for is the time(in months) taken by developers to finish the product.

Defects stand for Total Number of errors discovered

Example:

Problem Statement: Take the Library management system case. Software developed for library will accept data from operator for issuing and returning books. Issuing and returning will require some validity checks. For issue it is required to check if the member has already issued the maximum books allowed. In case for return, if the member is returning the book after the due date then fine has to be calculated. All the interactions will be through user interface. Other operations include maintaining database and generating reports at regular intervals.

Major software functions identified.

1. User interface
2. Database management
3. Report generation

For user interface
Sopt : 1800
Sm : 2000
Spess : 4000

EV for user interface
EV = (1800 + 4*2000 + 4000) / 6
EV = 2300

For database management
Sopt : 4600
Sm : 6900
Spess : 8600

EV for database management
EV = (4600 + 4*6900 + 8600) / 6
EV = 6800

For report generation
Sopt : 1200
Sm : 1600
Spess : 3200

EV for report generation
EV = (1200 + 4*1600 + 3200) / 6
EV = 1800

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