Dynamic Memory Frequently Asked Questions in C.
Q1.What is dynamic memory allocation in C, and why is it important?
Dynamic memory allocation is the procedure of assigning the memory space during the run time or execution time.
Q2.How do you allocate memory dynamically in C?
The "malloc" or "memory allocation" method in C is used to dynamically allocate large blocks of memory with a specified size. This returns void pointer type which can be cast to any type of pointer. It does not initialize memory at execution time, so it initially initializes each block with a default garbage value.
The "calloc" or "contiguous allocation" method in C is used to dynamically allocate a fixed number of blocks of a specified type of memory. It is similar to Malloc() but has two different properties and they are:
It has two parameters or arguments compared to malloc().
each block is initializes with a default value of '0'.
Q3.What is the difference between malloc() and calloc() in C dynamic memory allocation?
The difference between calloc() and malloc() function is that calloc allocates memory and initializes each byte in the allocated memory to 0. Where as malloc() allocates a block of memory of a given size and does not initialize the allocated memory.
Q4.How do you release dynamically allocated memory in C using the free() function?
The free() function is used to free memory previously allocated using malloc(), calloc() or realloc(). It requires one argument, which is a pointer to a block of memory to deallocate.
The syntax : void free(void*ptr);
Q5.What are common pitfalls to avoid when working with dynamic memory allocation in C programs?
When working with dynamic memory allocation in C programs, many pitfalls cans must be avoided to ensure efficient and error-free memory management. Some of these pitfalls include:
1. Forgetting to free allocated memory.
2. Accessing memory beyond allocated boundaries.
3. Not checking for NULL after allocation.
4. Mixing up memory allocation functions.
5. Memory fragmentation.
Q6.How does memory leak occur in dynamic memory allocation, and how can it be prevented?
A memory leak in C occurs when a program allocates memory for a data structure, such as list, an array, or tree, but does not release it when it is no longer wanted. This means that the system takings up memory, but other parts of the code cannot reuse or access it.
There is a simple way to avoid memory leaks in programs written in C:
Have 2 global variables (at least 32 bit, but 64 bit is even better). These two variables will be initialized to 0 at the beginning of the program.
Q7.What is the role of the realloc() function in dynamic memory management in C?
The realloc() function is resizeto previously allocated blocks. It takes two arguments: a pointer to the previously allocated memory block and the new size in bytes. The return value is a pointer to an array block, which may or may not be the same as the previous point.
Q8.Can you provide an example of dynamically allocating memory for a data structure like an array or linked list in C?
For example, to allocate an integer array,use
int *arr = (int *) malloc(n * sizeof(int))
or
int *arr = (int *) calloc(n, sizeof(int))
where `n` is the chosen array size. Remember to free the allocated memory using `free()` when it is no longer needed.
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