Chapter 3 - Source Lines of code: Software Management Course -AUG Unversity
Welcome back! This is chapter 3 of the series explaining the Software Management course for AUG students — The computer system engineering department.
What is SLOC?
Source lines of code (SLOC) are:
- A software metric that is used to measure the size of a software program by counting the number of lines in the text of the program’s source code.
- It’s used to predict the amount of effort that will be required to develop a program.
- It’s used to estimate programming productivity once the software is produced.
- It can be used to measure either an existing program or a program yet to build.
Disadvantages of SLOC Metrics:
There are many disadvantages, but I will talk about the points that exist in our course.
- The difference in Languages:
Consider two applications that provide the same functionality one is written in Java and the other is written in C#:
- The number of function points would be exactly the same, but aspects of the application would be different.
- The lines of code needed to develop the application would certainly not be the same. As a consequence, the amount of effort required to develop the application would be different (hours per function point).
- Unlike Lines of Code, the number of Function Points will remain constant
- The lack of standardized definition:
Since the SLOC represent a count of unknown units, thus it would be an inaccurate sizing metric for comparison if SLOC measures are stated without definition.
Terminology and Definitions
- SLOC (Source line of code): non-blank, non-comment, logical source lines and usually measured by thousand (K)
- DSI(Delivered source instructions): non-comment, logical source lines, and excluded data.
- Productivity: total number of DSI divided by the total time in person-month required to complete the project. for example, the productivity for 20k lines that should be finished in 4 months is 20k/4=5k
The most popular SLOC measures are:
- Physical carriage returns: Included a count only of physical line ending.
- Physical SLOC: Included a count of non-blank, non-comment lines in a program source code.“the lines that do not contain blanks or comments”
- Logical SLOC: Measures the number of logical programming that may or may not cross over more than one physical line.
Another term You Should Know:
- Comment: Comment lines in code
- Physical Lines: Physical Lines are the program’s source code including comment lines.
- Logical Lines: Logical Lines are a number of executable statements
- Blank Lines: Lines in Code which is Blank
- Total Lines of code: Total Lines of code include Physical lines with Blank Lines
- Executable Physical: Physical executable source lines of code is calculated as the total lines of source code minus blank lines and comment lines.
- Executable Logical: Executable Logical is a number of statements that are executed.
Logical SLOC Counting Details:
The logical SLOC can be classified into four categories:
- The first category is based on what language statements should be included or excluded category.
- The second category is based on the source of SLOC used in the delivered product.
- The third category is based on the origin of the counted SLOC
- The fourth category is based on which SLOC should be counted in the delivered products.
Table 3.2 States the rules that apply to the first category:
Let’s see Table 3.1 which contains a detailed definition for counting logical SLOC as used in cost models:
There are some notes about this table:
- In code generation, if you change some code from version x to version y, then, you count the output. (Excluded)
- In code converting, if you convert code from language a to language b, then, you count the input. (Included)
- If you edit for example 1k lines in a library then you count only the percentage of the editing only from the edited part, and you do not count all of the library.
Let’s see Table 3.3 Page 122:
The previous table shows how you count the Physical carriage returns, Physical lines, and Logical lines.
Remember:
- Logical Lines are a number of executable statements e.g while, n++or int =… is a logical line
- Physical carriage returns included a count only of physical line ending. for example, the first line in the table is 1 and the second is 2 (1 for the second line and 1 for the previous line)
