ownership

问题 Using a simple linked list implementation in C, how do I tell Splint that I am transfer ownership of data ? typedef struct { void* data; /*@null@*/ void* next; } list; static /*@null@*/ list* new_list(/*@notnull@*/ void* data) { list* l; l = malloc(sizeof(list)); if (l == NULL) return NULL; l->next = NULL; l->data = data; return l; } I get this error message: Implicitly temp storage data assigned to implicitly only: list->data = data Temp storage (associated with a formal parameter) is

问题 I am learning Rust from The Rust Programming Language book available from No Starch Press but ran into an issue where the compiler did not behave as explained in the book in chapter 4 on p. 77. Chapter 4 of the book is discussing ownership, and the example on p. 77 is similar to this without the final println!() in main() (I've also added comments and the function from p. 76 to create an MCVE). I also created a playground. fn main() { let mut s = String::from("Hello world!"); let word = first

问题 I want to open a file and read its contents as a BufReader using lines() . I also want to be able to seek to the end of the file and write some new lines. Using let mut file lets me write to the file, but once I've given the file to the BufReader I can no longer write to it, as the main function no longer owns file : fn main() { let filename = "tt.txt"; // open a tt.txt file in the local directory let file = OpenOptions::new() .read(true) .write(true) .create(true) .open(filename) .unwrap();

问题 I would like my class to be: class NumberedString : public Object { public: String newName; short nameID; NumberedString(String &newName, short nameID) : newName(newName), nameID(nameID) {} }; HashMap uniqueStrs;//For later. An instantiation of this will be passed to a HashMap which takes over ownership of its the heap allocation: In HashMap.h (say): virtual result Add(const Object& key, const Object& value); Now this is where I get confused. I was allocating the String in the line that

问题 first post. Sorry if I screwed up the code rules. I'm trying to learn Objective C from the Big Nerd Ranch Guide. I'll post the example dealing with strong references. #import <Foundation/Foundation.h> @interface Asset : NSObject { NSSTRING *label; unsigned int resaleValue; } @property (strong) NSString *label; @property unsigned int resaleValue; @end So basically the NSString needs a strong reference whereas the int does not. I'm aware that NSString is an object, and I've read that if nothing

问题 In his February 2018 note titled "Memory Safety in Rust: A Case Study with C", Will Crichton wrote: Rust provides the ability to take ownership of raw pointers, which we do using slice::from_raw_parts_mut and Box::from_raw which tells Rust to treat the memory pointer as a heap-allocated array. After transferring ownership, assuming the memory is valid and of the right size/type, Rust applies its usual memory safety and containment checks. The relevant part of his code to which the above

问题 I'm having a play with Rust and, probably biting off far more than I can chew, am trying to write a module that will encapsulate my database traffic for the rest of the application. The code I'm struggling with is the following: pub fn create_statement(cypher: &str, params: &HashMap<&str, &str>) -> rusted_cypher::Statement { let mut statement = rusted_cypher::Statement::new(cypher); for (field, value) in params.iter() { statement.with_param(field.to_owned(), value.to_owned()); } return

问题 I want to take file ownership using win32 api, and I want my code to work on both xp and win7 anyway, here is what i came up with Function that changes the ownership of the file int ChangeFileOwner() { HANDLE token; char *filename = "c:\\file1.txt"; //(not owned by the current user) DWORD len; PSECURITY_DESCRIPTOR security = NULL; int retValue = 1; PSID sid; // Get the privileges you need if (OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &token)) { if(!SetPrivilege(

问题 When compiling the following code: fn main() { let mut fields = Vec::new(); let pusher = &mut |a: &str| { fields.push(a); }; } The compiler gives me the following error: error: borrowed data cannot be stored outside of its closure --> src/main.rs:4:21 | 3 | let pusher = &mut |a: &str| { | ------ --------- ...because it cannot outlive this closure | | | borrowed data cannot be stored into here... 4 | fields.push(a); | ^ cannot be stored outside of its closure What does this error mean, and how

问题 I have the following (trimmed down) Rust code: use std::collections::HashMap; struct Node { weight: f64, outbound: f64, } struct Graph { edges: HashMap<u32, HashMap<u32, f64>>, nodes: HashMap<u32, Node>, } impl Graph { fn mutate(&mut self) { for (key, value) in self.nodes.iter() { if self.edges.contains_key(key) { for (target, weight) in self.edges[key].iter() { self.nodes.entry(*target).or_insert(Node::new()).weight; } } } } } However, I cannot get the code to compile due to Rust ownership