I am a little confused on both pointers and reference.
From my understanding pointers are addresses in memory.
In general, they are both addresses in memory. Usually one speaks of pointers if arithmetic can be done on them and of references if not, but there are some language-specific variations.
If I pass a variable using pointers and reference to a function, any
manipulations of the variable in the function will change the original
But there are three reasons for passing something by reference:
- To avoid copying large amount of data to the stack.
- To modify the original variable.
- To support polymorphism, as the generated code does not know in advance how large the object will be and how to properly copy it.
Code using the second option is always more difficult to read than code using return values and if it is not used consistently, it is a sure way to create real mess. To distinguish this case from the other two C++ has the
const modifier. Unfortunately Java and C# don't (and their authors don't seem to understand why it is useful; might have something to do with the fact that many people sell
const in C/C++ as optimization tool which it certainly isn't).
I read online that passing by reference is not encouraged because it can get messy code easily.
High level languages hold everything by reference, because of the reason 3 above. They may pass the reference by value (just like passing pointer in C; the function can't change where the pointer points, but it can change content of the pointed object) or by reference (that is pointer-to-pointer; the function can make the variable point to different object), but it is always a reference to the actual object.
Java does that except for primitive numeric types and C# does it for everything that is
But passing by reference for the reason 2 above is indeed discouraged. One simply does not normally expect function to modify it's arguments, so better not do it.
I also read here (http://stackoverflow.com/questions/7058339/c-when-to-use-references-vs-pointers), that we should avoid pointers if we can.
That is C++-specific. References can't be set to
0 in older C++) so you don't have to check and references can't be
deleted, so you don't have to think whether you should.
My question is when should pointers and reference be used?
Wherever they have to be.
I know pointers are used in Xcode for strong references and reference
counting. Since, higher level languages like c# have garbage
collector, does that mean we shouldn't ever use pointers and reference
Managed languages (C#, Java, ...) don't have pointers at all. Pointers allow access to raw memory and that would interfere with the managed runtime. So they don't have them (C# does, in the special, "unsave", extension, to allow interfacing with plain old C libraries).