how to return current working directory from function?

has experience with high level programming languages. I read the Rust book and now trying to survive and understand how the "things" in Rust works. I would love that someone explain what the heck is - Ok(()) and how to deal with it? My goal is to return result from function in to the variable where the output:

 Finished dev [unoptimized + debuginfo] target(s) in 0.01s Running `target/debug/rcp ./file/ aba` Ok( "/home/tomand/rcp", ) 

Here is the full code:

use std::fs; use std::env; use serde_json; use regex::Regex; use std::path::Path; fn determinate_file_size(file: &str) -> u64 { fs::metadata(file).unwrap().len() } fn determinate_is_it_file_or_dirctory(arg: &str) -> &str { let file = "File"; let dir = "Directory"; let re = Regex::new(r"/").unwrap(); if re.is_match(arg) { return dir; } return file; } fn collect_user_arguments() -> Vec<String> { env::args().collect() } fn check_if_arguments_count_valid(args: &Vec<String>) -> bool { if args.len() == 3 { return true } help(); return false } fn get_current_working_dir() -> Result<T> { env::current_dir() } fn help() { println!("Examples:"); println!("rcp [srcfile] [destfile]"); println!("rcp [srcdir]/[srcfile] [destdir]/[destfile]"); } fn main() { let WORKING_DIR = get_current_working_dir(); let args: Vec<String> = collect_user_arguments(); if check_if_arguments_count_valid(&args) { let arg1 = &args[1]; let arg2 = &args[2]; println!("{:#?}", determinate_is_it_file_or_dirctory(&arg1)); } } 

Seems the compiler tried to give me some inspiration but eventually we miscommunicate in the end:

error[E0107]: this enum takes 2 generic arguments but 1 generic argument was supplied --> src/main.rs:42:33 | 42 | fn get_current_working_dir() -> Result<T> { | ^^^^^^ - supplied 1 generic argument | | | expected 2 generic arguments 

EDIT: I went with this approach:

fn get_current_working_dir() -> String { let res = env::current_dir(); match res { Ok(path) => path.into_os_string().into_string().unwrap(), Err(_) => "FAILED".to_string() } } 

It seems more practice is required to understand the Result type and how to manage it.

1 Answer

std::env::current_dir returns a std::io::Result<Pathbuf>, so you need to use that type in your wrapper method:

fn get_current_working_dir() -> std::io::Result<PathBuf> { env::current_dir() } 

Playground

Other nitpick:

const is not a type so let WORKING_DIR: const = get_current_working_dir(); is wrong, just let WORKING_DIR = get_current_working_dir(); is enough.