What are two common defensive coding techniques?

What are two common defensive coding techniques?

• A. Check functional preconditions and postconditions
• B. Rely on global variables and hard-coded values
• C. Optimize for speed only
• D. Ignore input validation

Answer: (A)

Defensive coding centers on preventing errors by validating assumptions and enforcing expected behavior. Checking functional preconditions means confirming that inputs and the program state meet required conditions before running a function or operation. This early validation catches invalid or unexpected inputs, avoids cascading failures, and makes error handling clearer. Checking postconditions means verifying that, after execution, the function’s results and the program state fulfill what’s promised and that any invariants are preserved. This helps detect deviations from the intended contract and provides a reliable way to catch bugs right at the boundary of a function. Together, these two techniques embody defensive programming: verify inputs before use and verify outputs after execution, ensuring robustness and predictable behavior. The other options don’t reflect this approach—relying on global variables and hard-coded values introduces fragility; focusing only on speed ignores safety; and ignoring input validation leaves the system exposed to improper or malicious data.

Defensive coding centers on preventing errors by validating assumptions and enforcing expected behavior. Checking functional preconditions means confirming that inputs and the program state meet required conditions before running a function or operation. This early validation catches invalid or unexpected inputs, avoids cascading failures, and makes error handling clearer.

Checking postconditions means verifying that, after execution, the function’s results and the program state fulfill what’s promised and that any invariants are preserved. This helps detect deviations from the intended contract and provides a reliable way to catch bugs right at the boundary of a function.

Together, these two techniques embody defensive programming: verify inputs before use and verify outputs after execution, ensuring robustness and predictable behavior. The other options don’t reflect this approach—relying on global variables and hard-coded values introduces fragility; focusing only on speed ignores safety; and ignoring input validation leaves the system exposed to improper or malicious data.