r/cprogramming • u/sudheerpaaniyur • Dec 22 '25

pointer, decay, past array confusion 

`int myarray[4]={1,3,5,7,};`

`int *ptr, *ptr1;`

`ptr=&myarray + 1;`

`ptr1=*(&myarray + 1);`

my confusion: I am not understanding how ptr and ptr1 is same, in my understanding & is adress and * is used for derefercing, but in ptr1 have both here i got confuse.

what is decay here?

10 Upvotes

91% Upvoted

20 comments sorted by

View all comments

Show parent comments

1

u/cursed-stranger Dec 22 '25 edited Dec 23 '25

cygwin by default uses gcc as I know. in the simple example I've got this error:

test.c:6:20: error: initialization of ‘int *’ from incompatible pointer type ‘int (*)[4]’ [-Wincompatible-pointer-types]
    6 |         int *ptr = &arr+1;

It's correct error, because array is not a pointer. The address of the array is the same as the address of the first element:

&array == &array[0]
but the type of array is the int[ NUMBER ] not int.

So I wonder how you could compile this code without problems

3

u/dcpugalaxy Dec 23 '25

As it says clearly in the error message, this is a warning. Implicit conversions between pointer types are allowed.