题目
题目

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

单项选择题

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

选项
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
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
C.The pointer p is being converted from its previous type to now be of type "pointer to data_t"
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
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
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标准答案
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思路分析
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 a......Login to view full explanation

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类似问题

Inside the main() function of "particletest.c", we have now allocated an array of 1024 particles of type Particle. As we would like this number to be flexible in the future, the array is allocated dynamically using malloc(), which is part of the C Standard General Utilities Library. 在"particletest.c"的 main()函数中，我们动态分配了一个包含 1024 个 Particle 类型粒子的数组。为了使这个数字在未来可以灵活调整，我们使用 C 标准通用工具库中的 malloc()函数来动态分配数组。 Our implementation uses the following approach: 我们的实现采用了以下方法： #include <stdio.h> #include <stdlib.h> #define NUM_PARTICLES 1024 ··· int main() { Particle *particles = (Particle *)malloc(NUM_PARTICLES); ··· } Despite the fact that the declaration seems correct, the code produces a segmentation fault exception in some experiments. However, in some other situations, no apparent errors are produced. Do you consider the declaration and allocation to be correct (and, thus, the error located somewhere else in the source code)?

Inside the main() function of "particletest.c", we have now allocated an array of 1024 particles of type Particle. As we would like this number to be flexible in the future, the array is allocated dynamically using malloc(), which is part of the C Standard General Utilities Library. Our implementation uses the following approach: #include <stdio.h> #include <stdlib.h> #define NUM_PARTICLES 1024 ··· int main() { Particle *particles = (Particle *)malloc(NUM_PARTICLES); ··· } Despite the fact that the declaration seems correct, the code produces a segmentation fault exception in some experiments. However, in some other situations, no apparent errors are produced. Do you consider the declaration and allocation to be correct (and, thus, the error located somewhere else in the source code)?

Which header file must be included to use dynamic memory allocation functions like malloc and free?

Select the true statement

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