Question

The "Cyclomatic Complexity" of a software module is primarily used to estimate:

• A. The number of lines of code (LOC).
• B. The number of linearly independent paths through the source code.
• C. The total memory consumption of the module.
• D. The time required for integration testing.

Hint:

To quickly estimate Cyclomatic Complexity without drawing a graph, count the number of "decision" words (if, while, for, case) and add 1.

Answer 1

The Correct Option is B

Concept:
Cyclomatic complexity is a software metric developed by Thomas J. McCabe in 1976. It is used to indicate the complexity of a program by measuring the number of linearly independent paths through a program's source code. A "linearly independent path" is a path through the code that introduces at least one new edge (link) not contained in any other path.

Step 1: Understanding the Control Flow Graph (CFG).
To calculate this metric, the code is represented as a directed graph where:
• Nodes: Represent the smallest units of commands or executable statements.
• Edges: Represent the flow of control between these statements. If the code has many decision points (if-else, switches, loops), the graph becomes more complex, and the number of paths increases.

Step 2: The Calculation Formula.
The formula for Cyclomatic Complexity $V(G)$ is: \[ V(G) = E - N + 2P \] Where:
• $E$ = Number of edges in the graph.
• $N$ = Number of nodes in the graph.
• $P$ = Number of connected components (usually 1 for a single module). Alternatively, it can be calculated as: $\text{Number of Predicate Nodes} + 1$.

Step 3: Significance of the Metric.
A higher cyclomatic complexity indicates a higher probability of errors and makes the code harder to test. Specifically, the complexity value tells a tester exactly how many test cases are required to achieve "Basis Path Coverage"—ensuring that every single unique path through the code is executed at least once.