Tanvi Tanvi - 1 year ago 77
C Question

Why *pointer_name behaves differently in 1D and 2D array

Why is it that when

is used in 1D array it gives the value in the array whereas
in 2D array gives an address instead. Isn't
supposed to tell what is stored, so why is output an address instead of
(the value in array)?

int main(){
int a[3][4] = {
{40, 1, 2, 3} ,
{4, 5, 6, 7} ,
{8, 9, 10, 11}
int (*p)[4] = a;

int b[4] = {3,4,8,5};
int *q = b;

printf("%d, %d",*q, *p);// output- 3, 10485040

return 0;

Answer Source

Because p is a pointer to an array. When you dereference p the array will decay to a pointer to the first element. Doing *p and &(*p)[0] is equivalent (and also equivalent to &a[0][0]).

If you want to print the first element then you need to dereference both pointers, i.e. **p.

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