I have trouble understanding this code

This might be a stupid question:tongue:, but I thought arrays start from index 0. So when we say print_array(data, 3)why is it only printing 10 20 30? why 40 is not included? isnt 40 index 3?!
I will appreciate if anyone can clarify this for me.

Code:

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#include <stdio.h>
void print_array(int *p, int size) {  /* int *p could have been written as int p[] */  int idx = 0;
  for (idx = 0; idx < size; idx++) {      printf("%d\n", p[idx]);  }
  printf("In print_array function size of array using sizeof: %ld\n", sizeof(p));}
int main() {  int data[] = {10, 20, 30, 40, 50, 60};
  print_array(data, 3);  /* data = NULL;  What happens if we try this assignment? */
  printf("Size of data array using sizeof: %ld\n", sizeof(data));
  return 0;}

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Code:

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out put is:
10
20
30
In print_array function size of array using sizeof: 4
Size of data array using sizeof: 24

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for (idx = 0; idx < size

so that is while idx < 3 = 0,1,2

and that look right as you are asking for 3 units,
print_array(data, 4); // ask for 4 units 0-3

Think of it saying print 3 elements versus what index to print.