For my C application I tried to initialize memory. I am aware of the slower calloc, but fortunatelly there is no need to track performance.
I need memory space for just one unsigned int element (up to 65535).
This is the part of my code that doesn't work:
//Declaration
unsigned int part1;
//Allocation
part1 = (unsigned int) calloc (1,sizeof(unsigned int));
That throws the compiler warning:
warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
Why does the above code doesn't work, where...
unsigned long size;
size =(unsigned long) calloc (1,sizeof(unsigned long));
...works great?
Thank you!
calloc returns void* so you should use it like
unsigned int* part1 = calloc (1,sizeof(*part1));
then assign it like
*part1 = 42;
If you have allocated space for several elements
part1[0] = 42; // valid indices are [0..nmemb-1]
may be clearer.
Note that you also have to free this memory later
free(part1);
Alternatively, if you only need a single element, just declare it on the stack
unsigned int part1 = 42;
Regarding why casting a point to unsigned long doesn't generate a warning, sizeof(void*)==sizeof(unsigned long) on your platform. Your code would not be portable if you relied on this. More importantly, if you use a pointer to store a single integer, you'd leak your newly allocated memory and be unable to ever store more than one element of an array.