What is the difference between saying something like root->data and root.data?

Question

As the title states, what is the difference between -> and . I thought they were the same thing?

Erik Eidt · Answer 1 · 2016-09-28T22:30:32.890

6

These are different operators, though related.

In C, . is field selection, and -> combines pointer dereference and field selection. So a->b is equivalent to (*a).b or more correctly (*(a)).b.

Many languages don't have both . and ->. In C# and Java, for example, which don't have ->, the . operator does both dereference and field selection as in -> in C. However, in C# and Java, . also does selection from a namespace, which does not involve dereferencing (more like C++'s :: operator).

Note: C# does have an unsafe construct that allows for unsafe/raw pointers, and also does actually have the -> operator to work with them. However, you won't encounter -> unless you're working in unsafe code.

edited Sep 28 '16 at 22:30

answered Sep 28 '16 at 22:25

Erik Eidt

33,747

In C# and Java (as of Java 8) -> is used in lambdas – yitzih Sep 28 '16 at 22:39
2

@yitzih In C# at least, -> remains a pointer dereference like C++ when you compile as unsafe. Lambdas are =>. – Kevin Fee Sep 28 '16 at 22:43
@yitzih, good catch. I'm so used to C# and Javascript, which both use => for lambdas, that I forgot Java uses -> for that! – Erik Eidt Sep 29 '16 at 04:17

What is the difference between saying something like root->data and root.data?

1 Answers1