I feel like the memory I allocated isn't actually being allocated to *ptr. Can someone please help?

Question

#include <stdio.h>
#include <stdlib.h>

int factorial(int* input);
int math(int* n, int* r, int* d);
int main() {
int n, r;
printf("nCr\nEnter n: ");
scanf("%d", &n);
printf("Enter r: ");
scanf("%d", &r);
int d = n - r;
int (*ptr)(int*) = factorial;
int (**fp)(int*) = &ptr;
fp = malloc(3*sizeof(*fp));
int facn = ptr(&n);
int facr = ptr(&r);
int facd = ptr(&d);
int result = math(&facn, &facr, &facd);
printf("= %d\n", result);
free(fp);
return 0;
}
int factorial(int* input) {
int d = 1;
for (int i = *input; i > 0; i--) d *= i;
return d;
}
int math(int* n, int* r, int* d) {
int result = *n/(*r * *d);
return result;
}

Answer 1

The function pointer can not be used for allocating, deallocating memory like normal pointers.. It will store the address of first location of the function code, not for any data.

int (*ptr)(int) = &factorial;
is enough..
If you want array of pointers then use
int (*ptr[])(int) { factorial, prime, <..> };

Hope it helps...

Answer 2

Jayakrishna🇮🇳 I checked an it says 8. Not really sure what to do from there. Also my concern is primarily that I don't think the double pointer I set to &ptr is allocating memory to ptr.

Answer 3

Jayakrishna🇮🇳 I just don't know how to allocate memory to a function pointer in general. If you could explain that then that would be great.

Answer 4

Ok thanks

Answer 5

You can check size allocated for pointer by
printf("%ld",sizeof(ptr));

Answer 6

It's the same as for ptr.
In other way, you can check

if( fp == NULL)
puts("Not allocated");
else
puts("Allocated");

But where are using fp, no need I think that. Between, Are you facing any problem with code actually?

Answer 7

hoping i understood your question currently...

You're welcome........