Cyclomatic Complexity Metric
Introduction to Cyclomatic Complexity (CC) metric
Cyclomatic Complexity in
Software Testing is a testing metric used for measuring the complexity of a
software program. It is a quantitative measure of independent paths in the
source code of a software program. Cyclomatic complexity can be calculated by
using control flow graphs or with respect to functions, modules, methods or
classes within a software program.
Independent path is
defined as a path that has at least one edge which has not been traversed
before in any other paths.
This metric was developed
by Thomas J. McCabe in 1976 and it is based on a control flow representation of
the program. Control flow depicts a program as a graph which consists of Nodes
and Edges.
Proposed enhancement factors, reasons for the
selection of enhancement factors and modification for CC metric with each
enhancement factor
Factor 1 - Find Type of basic control structures.
When type of Basic
control structure increase complexity of the program also increases.
Find Type of Basic
Control Structure
Complexity of basic
control structures (BCS) = Σ(Size of executable statement X Type
of basic control structure value according to the amount of contribution to the
complexity (CS))
Find Cyclomatic
Complexity of Basic Control Structure
Cyclomatic Complexity of
Basic Control Structure (CCBCS) = Cyclomatic complexity (CC) +
Complexity of basic control structures (BCS)
Factor 2 - Measuring the Nesting level of control structures
Reason - Complexity
α Nesting level of control structures
When Nesting level of
executable statement increase complexity of the program also increase.
This metric calculates the complexity at the nesting level considering the internal structure of the method and considers nesting to calculate the complexity of the class hierarchy
Find Complexity of
Nesting level of CS
Complexity of Nesting
level of Cs(CNL) = Σ(Size of executable statement (S) X Nesting
level of control structure value according to the amount of contribution to the
complexity (N))
Find Cyclomatic Nesting level of CS
Cyclomatic Complexity of
Nesting levels of Cs(CCNL) = Cyclomatic complexity (CC) +
Complexity of Nesting level of CS(CNL)
Factor 3 - Measuring the Complexity due to Inheritance
Reason Complexity
α Inheritance(I)
When inheritance count increase in program , as per
that complexity of the program also increase.
This metric calculates the complexity at the method
level considering the internal structure of the method and considers
inheritance to calculate the complexity of the class hierarchy.
The proposed metric is validated both theoretically
and empirically.
Find Complexity of Inheritance
Complexity of Inheritance (CI) =Σ(Size
of executable statement (S) X Value given for the level of
inheritance (I) )
Find Cyclomatic Complexity of Inheritance
Cyclomatic Complexity of Inheritance (CCI)
=Cyclomatic complexity (CC) + Complexity of Inheritance (CI)
Factor 4 - Find Size of executable statement
Reason Complexity
α Size of executable statement (S)
When size of executable statement count increase in program , as per that complexity of the program also increase.
Size of a class is used to evaluate the ease of
understanding of code by developers and maintainers.
Size can be measured in a
variety of ways. These include counting all physical lines of
code, the number of
statements, the number of blank lines, and the number of comments
lines. Lines of Code(LOC)
counts all lines. Non-comment Non-blank (NCNB) is sometimes
referred to as Source
Lines of Code and counts all lines that are not comments and not
blanks. Executable
Statements (EXEC) is a count of executable statements regardless of
number of physical lines
of code
Therefore, the proposed
metrics is helping to enhanced reliability, understandability and
maintainability of
executable statements of every program with high performance.
Find Complexity of Size
Complexity of size (CS)
= Σ( Size of executable statement (S) )
Find Cyclomatic Complexity
of Size
Cyclomatic Complexity of
Size (CCS) = Cyclomatic complexity (CC) + Complexity of size (CS)
Final modified equation(FME) by considering all
enhancement factors proposed
FME= ( C.Complexity of Size)
+ (C.Complexity of inheritance) +(C.Complexity of basic control structure) +
(C.Complexity of coupling)
FME = CCS + CCI + CCBCS + CCNL
Example of calculating the complexity using final
modified equation
Example 01
Flow Graph
Cyclomatic Complexity Calculation
E = number of edges = 11
N = number of nodes = 11
P = number of nodes that have exit = 1
CC =E – N + 2*P
=
11 -11 + 2*1
=
2
CC =2
CC = 2
Enhanced Cyclomatic
Complexity for each factors.
CCS
= CC + CS = 2 + 120 =122
CCI = CC + CI = 2 + 3 = 5
CCBCS
= CC + BCS = 2 + 19 = 21
CCNL
= CC + CNL = 2 + 0 = 2
Final Modified Equation
for Cyclomatic Complexity(FME ) =CCS + CCI + CCBCS + CCNL
=122 + 5 + 21 + 2
FME
=150
Final Modified Equation
for Software Complexity (FME) = CS + CI + BCS + NL
= 120 + 3 + 19
FME =142
Example 02
Flow graph
Cyclomatic Complexity Calculation
E = number of edges = 8
N
= number of nodes = 7
P
= number of nodes that have exit points
= 1
CC =E – N + 2*P
= 8 -7 + 2*1
CC
=3
CC =3
Enhanced Cyclomatic Complexity for each factors.
CCS = CC + CS = 3 + 69 = 72
CCI = CC + CI = 3 + 4 = 7
CCBCS = CC + BCS = 3 + 12 = 15
CCNL = CC + CNL = 3 + 0 = 3
Final Modified Equation
for Cyclomatic Complexity(FME) = CCS +
CCI + CCBCS +CCNL
= 72 + 7 + 15 + 3
FME
= 97
Final Modified Equation
for Software Complexity (FME) = CS + CI + BCS + NL
= 69 + 4 + 12 + 0
FME
= 85
Conclusion
|
Example |
FME(cc) |
FME(sc) |
|
1 |
150 |
142 |
|
2 |
97 |
85 |
And when Cyclomatic complexity factors enhanced Total Cyclomatic complexity also increased
References
A Critique of Cyclomatic Complexity as a Software
Metric
https://www.researchgate.net/publication/3407068_A_Critique_of_Cyclomatic_Complexity_as_a_
Software_Metric
Cyclomatic Complexity -
an overview | ScienceDirect Topics
https://www.sciencedirect.com/topics/computer-science/cyclomatic-complexity
Cyclomatic Complexity |
IEEE Journals & Magazine
https://ieeexplore.ieee.org/document/7725232
McCabe’s Cyclomatic
Complexity with Flow Graph
https://www.guru99.com/cyclomatic-complexity.html
That's all for the Cyclomatic Complexity Metric. Thank you for reading this Post. Good Bye.
