Rust for Systems Programming: Core Low-Level Concepts Quiz Quiz

Explore foundational Rust programming topics essential for systems development, focusing on ownership, memory safety, and low-level concepts. This easy quiz helps learners assess their understanding of Rust’s approach to systems programming, including borrowing, lifetimes, and safe concurrency.

1. Ownership Rules

   What happens when a Rust variable's ownership is moved to another variable in a function?

   1. The function panics at runtime
   2. Both variables can use the value
   3. The original variable becomes invalid and cannot be used
   4. The data is copied, and both variables remain valid

   Explanation: When ownership is moved in Rust, the original variable is no longer valid, ensuring memory safety. In contrast, copying is not the default for most types, so both variables can't use the value. The data isn't duplicated unless explicitly copied, and typical moves do not cause a runtime panic.

2. Borrowing References

   Which statement best describes borrowing in Rust using references?

   1. Allows temporary access without transferring ownership
   2. Always requires making a mutable reference
   3. Makes a shallow copy of the data
   4. Permanently gives data to another function

   Explanation: Borrowing lets you access data without giving up ownership, supporting safe concurrent and sequential code. Permanent data transfer would be a move, not borrowing. References don't involve shallow copying, and borrowings can be either mutable or immutable, not always mutable.

3. Mutable vs. Immutable References

   How many mutable references to a variable can exist at one time in a Rust program?

   1. Two mutable references per variable
   2. Only one mutable reference at a time is allowed
   3. Zero or one hundred, depending on the context
   4. Any number, but only if they are used sequentially

   Explanation: Rust allows only one mutable reference to a variable at any given time, which prevents data races. You cannot have any number even if they are sequential unless earlier borrows end. Two or more mutable references are not permitted, and the last option exaggerates to make a confusing point.

4. Stack vs Heap Allocation

   Which of the following best describes a value stored on the stack in Rust?

   1. It is of fixed size and lives until the variable goes out of scope
   2. It can change size dynamically during execution
   3. It always causes a memory leak
   4. It is manually allocated and freed by the developer

   Explanation: Stack-allocated values must be of fixed size and live only until their scope ends, ensuring fast memory operations. Dynamically sized values require heap allocation. Stack memory is automatically managed, and memory leaks are rare due to Rust's safety guarantees.

5. Lifetimes in Functions

   Why might a function in Rust need explicit lifetime annotations for its parameters?

   1. To allow multiple return values from the function
   2. To specify how long references are valid relative to each other
   3. So the compiler can check for integer overflows
   4. To force manual garbage collection

   Explanation: Lifetime annotations are used so the compiler can verify that references do not outlive data they point to. Checking for integer overflows is handled separately and not related to lifetimes. Multiple returns are managed with tuples or structs, and Rust doesn't have manual garbage collection.

6. Unsafe Code Block

   Under which scenario is it necessary to use an 'unsafe' block in Rust?

   1. When binding variables with let statements
   2. When directly dereferencing a raw pointer
   3. When calling any generic function
   4. When using a for loop with integers

   Explanation: Dereferencing raw pointers can lead to undefined behavior, so Rust requires an 'unsafe' block for these operations. For loops and variable bindings do not require 'unsafe' as they are checked by the compiler. Generic function usage is also type-safe and does not need 'unsafe'.

7. Zero-Cost Abstractions

   What is meant by the term 'zero-cost abstraction' in the context of Rust systems programming?

   1. Abstractions that require zero typing by the programmer
   2. Abstractions that do not incur runtime performance overhead
   3. Abstractions that are free of syntax errors
   4. Abstractions that remove memory safety checks

   Explanation: Zero-cost abstractions offer high-level programming constructs without sacrificing runtime efficiency. Ease of typing or syntax errors are unrelated to run-time cost. Zero-cost abstractions do not compromise on safety; memory checks are still enforced unless intentionally bypassed.

8. Pattern Matching with Enums

   Which Rust feature enables safe, exhaustive handling of all possible values defined in an enum?

   1. Pattern matching with the match expression
   2. Using 'goto' statements for branching
   3. Defining methods on primitive types
   4. Dereferencing pointers with star notation

   Explanation: Pattern matching with 'match' ensures all enum variants are handled explicitly, promoting safety and correctness. Pointer dereferencing is not related to enum handling. Methods on primitives and 'goto' statements do not provide exhaustive branching or cover enum cases.

9. Thread Safety via Ownership

   How does Rust's ownership model contribute to thread safety in concurrent systems programming?

   1. It guarantees all code runs in a single thread
   2. It enforces clear data ownership to prevent data races
   3. It requires explicit memory allocation for each thread
   4. It hides synchronization primitives from developers

   Explanation: Rust’s ownership model ensures that only one thread can own mutable data at any time, preventing data races. Rust allows multi-threading and does not limit all execution to one thread. Memory management is automatic, and synchronization primitives are explicitly available, not hidden.

10. Slices and Array Views

    What is a slice in Rust, as applied to an array or vector?

    1. A random number generator for the array
    2. A single element of the collection
    3. A dynamically-sized view into a contiguous sequence of elements
    4. A copy of the data stored elsewhere in memory

    Explanation: A slice provides a flexible view into a portion of an array or vector without copying the data. It is not a data copy nor a single element. The distractor involving a random number generator is unrelated to the concept of slices.