| 1 |
Fernando Rodriguez wrote: |
| 2 |
> On Monday, August 03, 2015 6:41:22 PM walt wrote: |
| 3 |
> > That line declares *hostname as a constant and then the statement below |
| 4 |
> > proceeds to assign a value to the 'constant'. I wonder how many hours |
| 5 |
> > of frustration have been suffered by student programmers while trying to |
| 6 |
> > understand the logic behind that. |
| 7 |
> |
| 8 |
> Because it's not a constant, it's a pointer-to-constant :) |
| 9 |
Both of you are right, you can read the declaration in both ways: |
| 10 |
hostname is of type "pointer to const char". |
| 11 |
*hostname is of type "const char". |
| 12 |
|
| 13 |
But in this case it is not "*hostname", that get's a value assigned, it's simply "hostname". If you do not set hostname to NULL it stays uninitialised, which means its value is what the actual memory is set to - quite undefined. |
| 14 |
Correct initialization is really important and should be done consequently so it gets an automatism ;) (would avoid issues like this) |
| 15 |
|
| 16 |
> |
| 17 |
> const char *hostname; /* pointer to constant char */ |
| 18 |
> char *const hostname; /* constant pointer to char */ |
| 19 |
> const char *const hostname; /* constant pointer to constant char */ |
| 20 |
> |
| 21 |
> Is that confusing enough? |
| 22 |
> |
| 23 |
> -- |
| 24 |
> Fernando Rodriguez |
| 25 |
> |
Archives