Rust: Copy vs Move Semantics

In Rust, what determines whether the assignment s2 = s1 performs a copy or a move operation?

What does the Copy trait imply for the assignment s2 = s1 when Student implements it?

If the Name field of the Student struct is a pointer to a heap-allocated string, what happens to the string's memory when s2 = s1 is executed and Student implements Copy?

Given a Student struct with a Name field that is a pointer to a heap-allocated buffer, and assuming Student implements the Copy trait, what potential issue could arise if the string pointed to by Name is modified after the assignment s2 = s1?

Consider the scenario where Student contains a field transcript: File, where File represents an open file handle. If Student implemented Copy, what subtle but potentially devastating issue could arise after the assignment s2 = s1?

Why does the operation s += "A larger string" imply the creation of a mutable reference?

In Rust, what is the primary purpose of references?

Consider the following Rust code snippet:

let mut s = String::from("hello"); let r1 = &s; let r2 = &s; println!("{}, {}", r1, r2);

Why does this code compile without errors?

What is the significance of the len() method requiring an immutable reference (&self) in the String struct in Rust?

What is the key difference between a mutable and an immutable reference in Rust, concerning borrowing rules?

Consider the following scenario in Rust:

let mut s = String::from("hello");
let r1 = &mut s;
// some operation
let r2 = &mut s; //This line causes a compile error

Why does this code snippet result in a compile-time error?

Given the following Rust code:

fn modify_string(s: &mut String) {
    s.push_str(", world!");
}

fn main() {
    let mut my_string = String::from("hello");
    let len_before = my_string.len();
    modify_string(&mut my_string);
    let len_after = my_string.len();
    println!("{} {}", len_before, len_after);
}

Predict the output of this program.

Consider a scenario where you have a complex data structure in Rust, and you want to allow multiple parts of your code to read from it concurrently, but only one part to modify it at any given time. How would you achieve this safely using Rust's borrowing rules and standard library features without using unsafe code?

In the given C/C++ code snippet, what is the primary risk associated with printf("%s\n",s2); after delete []s1; s1 = nullptr;?

What is the immediate consequence of the line char* s2 = s1; in the provided C/C++ code?

What is the main problem the code tries to highlight in the assignment char* s2 = s1?

In the context of the code, what does it mean to 'duplicate the pointer'?

What is the potential outcome if s2 accesses the memory location after s1 has deallocated it using delete[] s1?

In the context of memory management, what is the significance of setting s1 = nullptr after delete []s1;?

If you wanted s2 to have its own independent copy of the string "abc" after the line char* s1 = new char{"abc"};, which of the following approaches would be most appropriate in C++?

Insanely difficult question: Suppose a hypothetical language, 'LangX', has similar pointer behavior to C/C++ but introduces a compile-time feature called 'Ownership Verifier'. This verifier tracks pointer assignments and deallocations. How would 'Ownership Verifier' likely react to the given code, and what change would it suggest to ensure memory safety, without using garbage collection?

In the provided Rust code, what is the primary issue that arises from modifying the String s after creating slice_of_s?

What does the term "dangling pointer" refer to in the context of the provided Rust code?

In the given Rust code, what is the value of s.len after the line s.push_str("DDDDD"); is executed?

In the context of the code provided, what is the value of slice_of_s.size?

What is the primary reason Rust's borrow checker doesn't prevent the dangling pointer issue in the provided example, considering the code compiles successfully?

Given that the String type in Rust can reallocate its underlying buffer, under what condition is reallocation most likely to occur when using the push_str method?

Suppose the initial capacity of String s is exactly enough to hold "AABBBCC" without any extra space. After creating slice_of_s = &s[2..5], what is the minimum capacity that s must have before the push_str operation to prevent reallocation and avoid creating a dangling pointer?

Consider a modified scenario where, instead of push_str, we use insert_str to insert "DDDDD" at the beginning of s after creating slice_of_s. If this operation causes reallocation, describe a potential strategy to mitigate the dangling pointer issue, assuming direct memory manipulation is unsafe and discouraged in Rust.

In Rust, what is the primary purpose of using immutable references?

In the provided Rust code snippet, what will be the value of s.len after the line s += "A larger string"; executes, assuming the code compiles successfully?

Given the Rust code and the stack analysis, what is the most likely data type stored at the memory location s.chars?

What would happen if you tried to modify the value referenced by ref_to_s_1 directly (e.g., ref_to_s_1.push_str("test");) after the line let ref_to_s_1: &String = &s;?

Why do immutable references prevent data modification?

In the given code snippet, what is the significance of the stack alignment (8 bytes) in the context of memory management?

Given that ref_to_s_1, ref_to_s_2, and ref_to_s_3 are all immutable references to s, and s is later modified, what mechanism in Rust ensures that these references do not lead to data corruption or undefined behavior?

Insanely Difficult: Consider a scenario where the println! macro is replaced with a custom function that uses unsafe Rust to bypass the borrow checker. If this custom function were to access ref_to_s_1 after s has been reallocated due to growing beyond its initial capacity, what is the most likely outcome?

In C, what is the likely outcome of attempting to printf the value pointed to by s2 after s1 has been deleted and set to nullptr, where s2 was initially assigned the same pointer value as s1?

In the provided C code examples, which scenario correctly avoids a double free or use-after-free vulnerability when dealing with dynamically allocated strings?

In Rust, what is the default behavior when assigning one variable to another, where the underlying type does not implement the Copy trait?

Which of the following data types in Rust automatically implement the Copy trait by default?

In Rust, considering ownership rules, what happens when a variable x is passed as an argument to a function my_function(x)?

Given the Rust code let s = String::from("hello"); let s2 = s; println!("{s}");, what is the expected compiler error and the reason behind it?

In Rust, if a function print_s takes ownership of a String argument, what happens to the variable passed to print_s in the calling function?

Consider a scenario in Rust where you want to allow a function to modify a String without taking ownership. Which approach should you use?

In Rust, the concept of 'borrowing' allows you to do what?

Insanely difficult: Suppose you have a complex data structure in Rust, a Graph represented as struct Graph { nodes: Vec<Node> } where Node contains multiple String fields and internal references. You need to implement a method split that divides the graph into two independent subgraphs, ensuring no shared ownership or references between them. The original Graph should be consumed in the process. What is the most idiomatic and memory-safe approach to achieve this, considering Rust's ownership and borrowing rules?

What is the Copy trait in Rust?

What is trait?

What happens during Copy?

s2 = s1 with Copy Trait

Validity after Copy?

delete []s1; s1 = nullptr;

Problem with printing 's2' after deleting 's1'?

Multiple owners (pointers) of same memory?

Dangers of duplicating pointers?

What is a trait in Rust?

Copy trait in Rust

Move trait (conceptually) in Rust

Move vs Copy

Heap

Stack

String Type

Reference

Borrowing

Immutable References

Offset

Capacity

Mutable String (String)

String Slice

push_str

Dangling Pointer

Memory Reallocation

Memory Deallocation

Borrowing Rules

Invalid Slice

Non-static Method References

Mutable Reference

+= and Mutable References

.len() and Immutable References

String::len(&self)

Multiple Immutable References

Undefined Behavior (C)

Move (C)

Copy (C)

Ownership (Rust)

Move Operation (Rust)

Copy Trait (Rust)

Ownership Rule Application

Borrow of Moved Value Error

Ownership Transfer to Function

Error E0382 (Rust)