Trait alloc::fmt::Pointer

1.0.0 · source ·

pub trait Pointer {
    // Required method
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}

Expand description

p formatting.

The Pointer trait should format its output as a memory location. This is commonly presented as hexadecimal.

For more information on formatters, see the module-level documentation.

Examples

Basic usage with &i32:

let x = &42;

let address = format!("{x:p}"); // this produces something like '0x7f06092ac6d0'

Run

Implementing Pointer on a type:

use std::fmt;

struct Length(i32);

impl fmt::Pointer for Length {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // use `as` to convert to a `*const T`, which implements Pointer, which we can use

        let ptr = self as *const Self;
        fmt::Pointer::fmt(&ptr, f)
    }
}

let l = Length(42);

println!("l is in memory here: {l:p}");

let l_ptr = format!("{l:018p}");
assert_eq!(l_ptr.len(), 18);
assert_eq!(&l_ptr[..2], "0x");