![pointer size in c pointer size in c](https://dyclassroom.com/image/topic/c/pointers-variables-representation/ptr-var.png)
But what does &ara holds? Let’s print the values of them. Like here ara holds the address of the first element of this array. We know t hat the name of array holds the address for the first element. In the next line we used pointer arithmetic to do the actual job. So in the main function, we declared an array and then we assigned values to that. Okay don’t start abusing me, I’m going to explain what I did. Today we’ll learn about a small pointer hack, so that we will be able to find the size of an array without using ‘sizeof’ operator.
![pointer size in c pointer size in c](https://www.freecodecamp.org/news/content/images/size/w2000/2020/12/pointers.png)
#Pointer size in c plus#
(Yes, in the particular code, I use pixel8_t, pixel16_t and pixel32_t now, plus a pixel_t of course).We can find the size of an array in C/C++ using ‘sizeof’ operator. You don't need to fix up all the type-casts.
#Pointer size in c code#
If I had to typecast, my code would look very messy (I actually cleaned up typecasting this way it can make a huge difference in how your code look).Īnother advantage is that you do not have to go through every reference in case you one day need to change a uint16_t to a pixel16_t. I can do this, because I know the memory location will always be divisible by 4. When I need the 16-bit pointer, I read address16. When I need the 32-bit pointer, I read address32. When I set the address, I write to 'address'. Now the above is not critical code, and all pointers are of the same size. Here's my solution to a problem where I need to supply a pointer to memory, but I do not know what datatype it actually points to it can be one of 3 types: Personally, I avoid typecasting if possible. I've used structures to hold some data, which could be of different types myself. Why I mention the structure, is because it's likely that aps would store a pointer to something as a structure member or directly in memory. There are parts of my reply that are not always valid, and parts of your reply, which also are valid in some cases. In such cases, we can only typecast and hope we're doing the right thing, because if something changes, we won't get a warning. DMA SrcAddr, DstAddr and LLI for instance). Sadly, with microcontrollers, it's very difficult to avoid it completely, because almost all hardware registers are defined as uint32_t, not pointers, although they are in fact pointers to memory areas (eg.
![pointer size in c pointer size in c](https://i.ytimg.com/vi/_EaAZYSvBog/sddefault.jpg)
If I can, I try avoiding typecasts, or resolve them.
#Pointer size in c 64 Bit#
If one pointer is 32 bit and the other is 64 bit, then there will be room for a 64 bit pointer, but there's also room for the 32-bit pointer.Ī typecast would not work with structures, because then you would have to know in advance which pointer type is largest, and if your guess is wrong, you will overwrite other members of the structure (or write past the end of the structure).Īll that said, I rarely find that it is necessary to do these things anymore. Thus the largest pointer size will be the dominating size. My intention of the code snippet is to reserve enough space for both pointer types in for instance a structure.
![pointer size in c pointer size in c](https://www.jquery-az.com/wp-content/uploads/2020/06/2_1-C-pointer.png)
That said, as above, it is highly highly probable to be true on every implementation I can think of, so it is unlikely you will run into any problems. The best thing to do would be to add some compile time asserts to raise an error if the two ever differ. You can't - if you rely on this you are coding outside of the standard. If so again how can we guarantee the sizeof (function_pointer) = sizeof(data_pointer)? Data pointers will always be the same data width, as C allows cast to void* and back again, so that "has to work". "Pragmatically assume" - probably - I'm not aware of any cases where the two differ in reality. If you are coding to the standard then C provides no guarantees that function pointers are the same width as data pointers (conceptually allowing function pointers to carry around additional payload in addition to an address). Can I ALWAYS assume that the sizeof(function_pointers) = sizeof(void *) = sizeof(char *)? I've a question regarding C programming on ARM processors.