# Error code E0641

Attempted to cast to/from a pointer with an unknown kind.

Erroneous code example:

ⓘ

    let b = 0 as *const _; // error

Run

Type information must be provided if a pointer type being cast from/into another type which cannot be inferred:

    // Creating a pointer from reference: type can be inferred
    let a = &(String::from("Hello world!")) as *const _; // ok!

    let b = 0 as *const i32; // ok!

    let c: *const i32 = 0 as *const _; // ok!

Run

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