Sorry for the rudimentary question, I'm new to Rust and ink!

I get a lot of errors when I run cargo +nightly contract test. I have checked the official site for the usage of ink_storage::Mapping, but am I implementing it properly?

error[E0614]: type `u128` cannot be dereferenced
   --> lib.rs:102:26
102 |             let token1 = *self.token1Balance.get(&caller).unwrap_or(0);
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

enter image description here

repo is bellow:https://github.com/tnkshuuhei/WasmAMMcontract/lib.rs

1 Answer 1


IMO, this is a pure-rust question. You'd better ask at https://stackoverflow.com/questions/tagged/rust.

Check https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.

Remove the * before the expression.

u128 is can not be dereferenced.

You only need to do that if the type is &u128.

  • Indeed, I will use it with Stackoverflow. Anyway, I did as you advised and the error disappeared. Thank you very much!!
    – Steve
    Oct 9, 2022 at 11:31

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