创建和使用可变原始指针

// Let's take a mutable piece of data, a 4-byte integer in this case
let mut some_data: u32 = 14;

// Create a mutable raw pointer pointing to the data above
let data_ptr: *mut u32 = &mut some_data as *mut u32;

// Note: creating a raw pointer is totally safe but dereferencing a raw pointer requires an
// unsafe block
unsafe {
    *data_ptr = 20;
    println!("Dereferenced data: {}", some_data);
}

上面的代码将输出：Dereferenced data: 20