free function - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to free the memory allocated to pointer ptr.

C

free([1]);

Drag options to blanks, or click blank then click option'

A*ptr

B&ptr

Cptr

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the address of the pointer instead of the pointer itself.

Passing a dereferenced pointer instead of the pointer.

The free function releases the memory pointed to by ptr. You should pass the pointer itself, not its address or dereferenced value.

2fill in blank

medium

Complete the code to allocate and then free an integer pointer.

C

int *p = malloc(sizeof(int));
if (p != NULL) {
    *p = 10;
    [1](p);
}

Drag options to blanks, or click blank then click option'

Adelete

Bfree

Crelease

Ddispose

Attempts:

3 left

💡 Hint

Common Mistakes

Using C++ keyword delete in C code.

Using non-existent functions like release or dispose.

In C, free is used to release memory allocated by malloc. Other options are not valid C functions.

3fill in blank

hard

Fix the error in the code to properly free the allocated memory.

C

char *buffer = malloc(100);
if (buffer != NULL) {
    // use buffer
    [1](buffer);
}

Drag options to blanks, or click blank then click option'

Afree

Bfree_ptr

Cfree(buffer)

Dfree(buffer);

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the address of the pointer instead of the pointer.

Including parentheses or semicolon inside the blank.

The free function should be called with the pointer itself, not its address. So use free(buffer); but since the blank replaces the function call, just free is correct to fill in.

4fill in blank

hard

Fill both blanks to correctly allocate and free memory for an integer array.

C

int *arr = [1](5 * sizeof(int));
if (arr != NULL) {
    // use arr
    [2](arr);
}

Drag options to blanks, or click blank then click option'

Amalloc

Bfree

Ccalloc

Drealloc

Attempts:

3 left

💡 Hint

Common Mistakes

Using calloc instead of malloc.

Using realloc without an existing allocation.

Forgetting to free the allocated memory.

malloc allocates memory, and free releases it. calloc also allocates but initializes memory to zero, realloc resizes allocated memory.

5fill in blank

hard

Fill all three blanks to allocate memory for a struct, assign a value, and then free the memory.

C

typedef struct {
    int id;
} Item;

Item *item = [1](sizeof(Item));
if (item != NULL) {
    item->id = [2];
    [3](item);
}

Drag options to blanks, or click blank then click option'

Amalloc

B42

Cfree

Dcalloc

Attempts:

3 left

💡 Hint

Common Mistakes

Using calloc instead of malloc.

Assigning a pointer instead of an integer to id.

Not freeing the allocated memory.

malloc allocates memory, 42 is assigned to the id field, and free releases the memory.