How Does Pointer Dereferencing Work in Go, and How Does It Compare to C/C ?

Understanding Pointer Dereferencing in Go

Pointer dereferencing, a fundamental operation in Go, involves accessing the value pointed to by a pointer variable. In the example mentioned in the question, pointers are used to manipulate a custom struct, Vertex.

Pointers and Structs

The original example showcased the creation of Vertex instances, including a reference to a Vertex instance using a pointer. In the modified example, the following occurs:

t := *q
q.X = 4

The first line dereferences the pointer q and assigns its underlying value to t, effectively creating a copy of the Vertex pointed to. Subsequently, modifying q.X updates the original Vertex instance but does not affect t because t holds a separate copy of the struct.

Avoiding Surprises with Pointers

To ensure that changes made through a pointer are reflected in other references, pointers should be used consistently. In the revised example below, both t and q point to the same underlying Vertex:

t := q

With this change, q.X = 4 now updates the Vertex instance accessed by both t and q, resulting in the expected output:

{1 2} &{4 2} {1 0} {0 0} &{4 2} {4 2} true

A Parallel in C/C

Contrary to the "extremely strange behavior" perception, C/C exhibits similar behavior when pointers are involved. The following C code demonstrates this:

Vertex v = Vertex{1, 2};
Vertex* q = &v;
Vertex t = *q;
q->x = 4;
std::cout << "*q: " << *q << "\n";
std::cout << " t: " << t << "\n";

The output is analogous to the modified Go example:

*q: { 4, 2 }
t: { 1, 2 }

Therefore, the pointer dereferencing behavior observed in Go aligns with the behavior of pointers in other programming languages, such as C/C .

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