The call to qsort must pass in a function pointer for a compare function to be u

Question

The call to qsort must pass in a function pointer for a compare function to be used in sorting the array. The function header for qsort is void qsort (void* base, //array to be sorted size_t n, //length of array size_t size, //size of each entry int (*cmp) const void *p, const void *q)//function pointer for compare function Which of the following function can be passed to qsort in order to sort an integer array? a) int int_cmp (int *p, int *q) {return *p - *q} b) int int_cmp (const void *p, const void *q) {return * (int *) p - * (int *) q;} c) int int_cmp (const void *p, const void *q) {return (int *) p - (int *) q;} d) int int_cmp (int *p, int *q) {return * (int *) p - * (int *)q;}

Explanation / Answer

Answer is B

Firstly we need to see whcih all function match requried function signature

Only b and c matches signature

Now in C we are chaning a void pointer to int pointer but are not derefercing it and subtraction is not allowed in pointer arithematic and it would result in error.

in b we are properly dereferncing the pointer and then returning the subtraction of those two values.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.