CODEWITHSUNDEEP
rust
Jimmay
Jimmay

Reputation: 1009

C-like pointer in structure

I'm trying to convert this simple C code to Rust:

#include <stdio.h>

struct n {
        int *p;
};

int main(void) {
    int i = 8;
    struct n m;

    m.p = &i;

    printf("%d ", i);
    printf("%d", *(m.p));

    return 0;
}

The output is "8 8".

There is no need for garbage collection or the other types of pointers which I have read about.

I've tried this:

struct n {
    p: *mut int
}

fn main() {
    let mut i: int = 8;
    let mut m: n;

    m.p = &i;

    println!("{} ", i);
    println!("{}", *(m.p));
}

But I get:

error: mismatched types: expected `*mut int`, found `&int` (expected *-ptr, found &-ptr).

Relating to this error:

m.p = &i;

There are no errors for the other lines.

I read that & is to get the address of a variable, but how can I store an address?

Upvotes: 0

Views: 4770

Answers (1)

A.B.
A.B.

Reputation: 16630

Change m.p = &i; to m.p = &mut i as *mut _;

A more idiomatic way would be this though:

let mut m = n {
    p: &mut i
};

And even more idiomatic would be not using a raw pointer unless necessary.

struct N<'a> {
    p: &'a mut int
}

Upvotes: 1

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