Dynamic memory allocation (heap) in Compiler Design - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Heap Memory Allocation

Which of the following best describes the heap in dynamic memory allocation?

A A large pool of memory used for dynamic allocation during program execution.

B A special register in the CPU that manages memory addresses.

C A memory region where variables are stored temporarily during program compilation.

D A fixed-size memory area used for storing local variables during function calls.

💡 Hint

Think about where memory is allocated when you use commands like malloc or new.

The heap is a large pool of memory used for dynamic allocation at runtime. It allows programs to request and release memory as needed, unlike the stack which is fixed and used for function calls.

📋 Factual

intermediate

Heap Allocation Characteristics

Which statement about heap memory allocation is TRUE?

A Memory allocated on the heap is automatically freed when a function ends.

B Heap memory size is fixed and cannot grow during program execution.

C Heap memory is faster to allocate and deallocate than stack memory.

D Heap memory allocation requires explicit management by the programmer.

💡 Hint

Consider who is responsible for freeing memory allocated on the heap.

Heap memory must be explicitly managed by the programmer, meaning they must allocate and free it manually. Unlike stack memory, it is not automatically freed when a function ends.

🚀 Application

advanced

Identifying Heap Allocation in Code

Given the following pseudo-code, which line is responsible for allocating memory on the heap?

1: int x = 10
2: int* p = allocate(4)
3: p[0] = x
4: free(p)

A Line 2

B Line 3

C Line 1

D Line 4

💡 Hint

Look for the command that requests memory dynamically.

Line 2 uses an allocate function to request 4 bytes of memory on the heap. This is dynamic allocation. Line 4 frees that memory.

🔍 Analysis

advanced

Consequences of Improper Heap Management

What is the most likely consequence if a program allocates memory on the heap but never frees it?

A The program will run faster due to cached memory.

B The program will crash immediately after allocation.

C The program will gradually consume more memory, possibly causing a memory leak.

D The program will automatically free the memory when the function ends.

💡 Hint

Think about what happens if memory is never returned to the system.

If memory allocated on the heap is not freed, it remains reserved and unavailable for other uses. Over time, this causes the program to consume more memory, leading to a memory leak.

❓ Reasoning

expert

Heap Allocation and Fragmentation

Why can frequent allocation and deallocation of different sized blocks on the heap lead to fragmentation?

A Because the CPU cache cannot store heap addresses efficiently.

B Because small free blocks get scattered between allocated blocks, making it hard to find large contiguous space.

C Because the stack grows into the heap causing overlap.

D Because the heap merges all free blocks into one large block automatically.

💡 Hint

Consider how free spaces are arranged after many allocations and frees.

Fragmentation happens when free memory blocks are scattered in small pieces between allocated blocks. This makes it difficult to allocate large contiguous blocks even if total free memory is sufficient.