Memory allocation flow - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to allocate memory for an integer pointer.

C

int *ptr = (int *)[1](sizeof(int));

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

Afree

Bmalloc

Csizeof

Dcalloc

Attempts:

3 left

💡 Hint

Common Mistakes

Using free instead of malloc causes errors because free releases memory.

Using sizeof alone does not allocate memory.

The malloc function allocates memory dynamically. Here, it allocates enough space for one integer.

2fill in blank

medium

Complete the code to release the allocated memory.

C

free([1]);

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

Aptr

BNULL

Cmalloc

Dsizeof

Attempts:

3 left

💡 Hint

Common Mistakes

Passing sizeof or malloc to free causes runtime errors.

Passing NULL to free does nothing but is not useful here.

The free function releases the memory pointed to by ptr.

3fill in blank

hard

Fix the error in the code to allocate memory for 5 integers.

C

int *arr = (int *)malloc([1] * sizeof(int));

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Asizeof(arr)

Bsizeof(int *)

C5

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using sizeof(arr) gives size of pointer, not the number of elements.

Using 0 allocates no memory.

To allocate memory for 5 integers, multiply 5 by the size of an integer.

4fill in blank

hard

Fill both blanks to create a loop that initializes the allocated array to zero.

C

for (int [1] = 0; [2] < 5; [1]++) {
    arr[[1]] = 0;
}

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

Ai

Bj

Ck

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in the loop causes errors.

Using a variable not declared causes compilation errors.

The variable i is used as the loop counter consistently in all parts of the for loop.

5fill in blank

hard

Fill all three blanks to safely allocate memory and check if allocation succeeded.

C

int *ptr = (int *)[1](sizeof(int) * [2]);
if ([3] == NULL) {
    printf("Memory allocation failed\n");
    return 1;
}

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

Amalloc

B10

Cptr

Dfree

Attempts:

3 left

💡 Hint

Common Mistakes

Using free instead of malloc causes errors.

Not checking if pointer is NULL can cause crashes.

Using wrong variable name in the if condition causes errors.

Use malloc to allocate memory for 10 integers. Then check if ptr is NULL to detect failure.