Pointers

A pointer is like a house address on a sticker.

It does not hold the value itself.

It tells you where the labeled box lives.

Go has no pointer math. That keeps pointers safer than in C.

Address with &

&x takes the address of x.

That is like writing down the house number.

You store that address in a pointer variable.

Looking inside with *

*p reads or writes the value at that address.

That is like opening the door and looking inside the box.

If you change *p, the original x changes too.

Pointers in functions

Pass a pointer so the function can change the original value.

Without a pointer, Go passes a copy.

Changes to a copy stay inside the function.

new

new(T) returns a pointer to a starter value of type T.

The box exists. It starts with the zero value.

nil pointers

A pointer's empty value is nil.

nil means the sticker points nowhere.

Always check before you follow a pointer if nil is possible.

Start with normal values. Use pointers when you need to share or change the original on purpose.