Consider the function call:

p = (data_t *)malloc((num - 1) * sizeof(data_t))

The intention of this function call is best described as:

Question

Consider the function call:

p = (data_t *)malloc((num - 1) * sizeof(data_t))

The intention of this function call is best described as:

BlackTom AI · Accepted Answer

The question presents a C snippet: p = (data_t *)malloc((num - 1) * sizeof(data_t)).
Option A: 'The pointer p, which already points at an array of num elements of type data_t, is being altered so that it now points at an array of num – 1 elements'. This describes pointer arithmetic or reassignment to a different-sized existing allocation, but malloc allocates a new block and does not imply that p originally pointed to a specific array of num elements. The statement confuses the role of malloc with resizing an existing allocation, which in C would require realloc, not a fresh malloc.
Option B: 'The pointer p is being assigned the address of a new array that has space to store num – 1 elements each of type data_t'. Here, the expression malloc((num - 1) * sizeof(data_t)) indeed asks the system for a block that can hold num - 1 elements of data_t, and (data_t *) casts the returned void* to the appropriate pointer type. This matches the purpose of allocating space for num - 1 elements.
Option C: 'The pointer p is being converted from its previous type to now be of type "pointer to data_t"'. The cast (data_t *) is present, but in C this is a cast from void* to data_t*, not a conversion of the pointer’s type in general; more importantly, the need to cast to data_t* does not indicate a change of the pointer’s type in isolation, and the core operation is allocation for num - 1 elements, not a type change.
Option D: 'The pointer p is being checked to make sure that the array it already points at contains space for at least num elements each of type data_t'. The code does not perform any check on an existing array; malloc returns a pointer to newly allocated memory or NULL, but there is no validity check or validation of an existing array in this statement. This option misinterprets the allocation expression as a pre-check.
Option E: 'The pointer p is being assigned the address of a new array that has space to store num + 1 elements each of type data_t'. This would correspond to malloc((num + 1) * sizeof(data_t)), not (num - 1). The given expression allocates space for num - 1 elements, so this option is incorrect based on the size calculation.
In summary, option B correctly reflects that malloc is used to obtain a new block capable of holding num - 1 elements of type data_t, with the appropriate cast applied to p. The other options describe scenarios or interpretations that do not align with how malloc and pointer assignment operate in C, including confusion about resizing, type changes, pre-checks, or incorrect element counts.

COMP10002_2025_SM2 Supplementary or Special Exam: Foundations of Algorithms (COMP10002_2025_SM2)- Requires Respondus LockDown Browser

Consider the function call: p = (data_t )malloc((num - 1) sizeof(data_t)) The intention of this function call is best described as:

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