Hi, fellow Crustaceans!
I am a newbie of Rust programming language. A nauplius.
Now I am learning THE BOOK. I have finished Chapter 8 and I tried the exercises.
Well, I'd have to say that Rust behaves quite differently from other programming languages in certain aspects and there were twists and turns when I tried to tell Rust what I wanted to do.
I finished exercise 3, but I suspect the code I wrote is not very Rust-y. So can anybody give me some advice on bettering the code?
main.rs
use std::collections::HashMap;
use std::io;
//Using a hash map and vectors, create a text interface to allow a user to add employee names to a department in a company.
//For example, “Add Sally to Engineering” or “Add Amir to Sales.”
//Then let the user retrieve a list of all people in a department or all people in the company by department, sorted alphabetically.
//utility functions are all place here
fn show_ops (){
println!("Please choose your op:");
println!("1 - List departments");
println!("2 - Add an employee to a department");
println!("3 - List employees in a department");
println!("4 - List employees in the company");
println!("0 - Exit");
println!("-----------------------");
}
fn get_op_code() -> i32 {
let mut info = String::new();
io::stdin().read_line(&mut info).expect("Failed to get input");
//info.trim().to_string();
let op_code:i32=match info.trim().parse(){
Ok(num) => num,
Err(_) => -1,
};
op_code
}
fn main() {
println!("Employee System");
//use this hashmap to store departments' info
let mut departments = HashMap::new();
let mut v:Vec=Vec::new();
//when inserting the vector, do not use &mut v, insert v directly
let mark = String::from("department");
departments.insert(mark, v);
departments.clear();
let mut deplen:usize = 0;
loop{
show_ops();
let opcode:i32 = get_op_code();
if opcode == 0 {//exit
println!("Good bye!");
break;
}else if opcode == 1{//list departments
deplen=departments.len();
println!("{} departments in record:",deplen);
for (key,_) in &departments {
println!("{}",key);
}
}else if opcode == 2{//add an employee
println!("To add an employee, use instructions like: add Tom to Sales");
println!("If the department doesn't exist, it will be created.");
let mut info = String::new();
let mut name:String = String::new();
let mut nholder:String = String::new();
let mut dept:String = String::new();
let mut dholder:String = String::new();
//get name and department
io::stdin().read_line(&mut info).expect("Failed to get input");
let mut i:i32=0;
//in fact we only need words in pos 2 and 4
for w in info.split_whitespace() {
i += 1;
if i == 2 {
name = String::from(w);
nholder = String::from(w);
println!("Name:{}",name);
}else if i == 4 {
dept = String::from(w);
dholder = String::from(w);
println!("Dept:{}",dept);
}else{
continue;
}
}
if name == "" || dept == ""{
println!("Input not complete?? Please try again.");
}else{
//check if department already exists
if departments.contains_key(&dept){
//add the employee to an existing dept
if let Some(x) = departments.get_mut(&dholder) {
x.push(nholder);
x.sort();
}
}else{
//create a new dept and add the employee
let mut v:Vec=Vec::new();
v.push(nholder);
v.sort();
departments.insert(dholder, v);
}
println!("Information added!!");
}
}else if opcode == 3{//list employees in a department
println!("Which department?");
let mut info = String::new();
io::stdin().read_line(&mut info).expect("Failed to get input");
if departments.contains_key(info.as_str().trim()){
println!("This department has:");
for n in departments[info.as_str().trim()].iter(){
println!("{}",n);
}
}else{
println!("{} department doesn't exist!!!",info.as_str().trim());
}
}else if opcode == 4{//list the whole company
println!("{} departments in the company:",&departments.len());
for (key,value) in &departments {
println!("{} department has:",key);
for n in value.iter(){
println!("{}",n);
}
}
}else if opcode == -1{
println!("Invalid Op!!!");
}else{
continue;
}
println!("-----------------------");
}
}