Hey all, teaching myself CPP through a few books (and a little bit of CS in general through CS50) and hit a road block.
I understand what pointers are, and understand they’re a big part of programming. My question is why?
What do you use pointers for? Why is forwarding to a new memory address preferable to just changing the variable/replacing what’s already at the memory address or at a new one? Is it because new data could exceed the size of that address already allocated?
Thanks in advance!
My advice is to learn pure C and make a few small programs with it. You’ll see very soon why pointers are necessary.
Pointers also allow you to do fun and dangerous things like casting between types!
For example, if you’re implementing your own memory allocator, at the base level your allocator only really cares about how many bytes are being requested (along with alignment, offset, other things) so you’d probably just implement it to return a char*, u8*, or void* pointing to the blob of memory you allocated with new, malloc, or whatever scheme you’ve cooked up. The calling code or higher level allocator code could then cast it to the actual type
I haven’t used pointers for a long time, I only use smart pointers nowadays. As for your question: just changing the variable/replacing what’s already at the memory address, the answer is also “sometimes you can’t” because some objects cannot be cloned or duplicated like sockets or threads.
It doesn’t “forward to”, it is a way to say “ehi, this data X is located at …”
Imagine having a big large data structure that takes up a lot of space. You have to pass it a function to perform some operations, but if pointers didn’t exist you would have to clone those data - which is expensive memory wise and probably time wise to. So instead of wasting either space or time, you simply pass a memory address to that data and using it you can access the original data.
Obviously if you have primitive data structures, such as integers, or that you know that aren’t expensive to clone, you can simply pass by value and call it a day (somewhere on learncpp theee is a very nice explanation of all of this)
I’ll be searching learnccp for your reference. Thanks! Also huge thanks to everyone who keeps pouring the knowledge in! You guys rock!
I’ll be searching learnccp for your reference
I have never used the learncpp site, IMHO you should use https://en.cppreference.com/w/ which is written by a guy that is really invested in the language.
There are things you’ll want to do that will eventually require pointers. For example, as soon as you want a type that contains a reference that could be rebound, you need a pointer.
If you want to implement polymorphism you’ll need pointers. If you instead want type erasure, you’ll need pointers to implement your type erasure container.
Sure it’s possible to implement a lot without pointers, but the code will be harder to write and will probably be slower.