Defensive programming practices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is defensive programming?

Defensive programming is a way to write code that expects and safely handles unexpected problems or errors to prevent crashes or bugs.

beginner

Why should you check function inputs in C?

Checking inputs helps catch wrong or dangerous values early, avoiding crashes or security problems later in the program.

intermediate

How can you handle errors in C defensively?

Use return codes or error flags to detect problems, and always check these before continuing to avoid unexpected behavior.

intermediate

What is the purpose of assertions in defensive programming?

Assertions check if assumptions in code are true during development. If not, they stop the program to help find bugs early.

beginner

Give an example of a defensive programming practice in C.

Before using a pointer, check if it is NULL to avoid crashes. For example: if (ptr == NULL) { handle error; }

What is a key goal of defensive programming?

A Make code run faster by skipping checks

B Avoid using error handling

C Write code only for expected inputs

D Prevent program crashes by handling unexpected inputs

Defensive programming aims to prevent crashes by safely handling unexpected inputs or errors.

Which of these is a defensive programming practice in C?

A Ignoring return values of functions

B Using global variables without checks

C Checking if pointers are NULL before use

D Assuming inputs are always valid

Checking pointers for NULL before use helps avoid crashes and is a defensive practice.

What does an assertion do in C?

A Automatically fixes bugs

B Checks if a condition is true and stops the program if not

C Runs only in production code

D Skips error checking

Assertions check conditions during development and stop the program if the condition is false.

Why should you validate inputs in your functions?

A To catch invalid data early and avoid errors

B To reduce code size

C To ignore user mistakes

D To make the program slower

Validating inputs helps catch invalid data early, preventing errors later.

Which is NOT a defensive programming practice?

A Ignoring error codes

B Checking for NULL pointers

C Using assertions during development

D Validating function inputs

Ignoring error codes is unsafe and not a defensive programming practice.

Explain what defensive programming is and why it is important in C.

Think about how to keep your program safe from unexpected problems.

Describe three defensive programming techniques you can use in C code.

Consider how to check data and handle errors before they cause crashes.