from-user

A tiny, highly simplified Rust input helper

Version: 0.2.3

A minimal library that provides two helpers for reading user input from stdin:

• single_line() — returns the raw line as a String.
• number() — tries to read a numeric line and return it as i32 (retries on invalid input).

This crate is intentionally small and easy to read — good for learning or small CLI experiments.

Quick start

Add the crate to your Cargo.toml (when published on crates.io):

[dependencies]
from-user = "0.2"

Note: when using the crate in Rust code, the crate name uses an underscore in use paths (hyphens become underscores):

use from_user::{single_line, number};

fn main() {
    let s = single_line();
    println!("you typed: {}", s);

    let n = number();
    println!("number: {}", n);
}

If you are testing locally without publishing, add it by path in your binary project's Cargo.toml:

[dependencies]
from-user = { path = "../from-user" }

API

pub fn single_line() -> String

Reads one line from stdin and returns it as a String (including trailing newline if present). It currently prints a short message on read_line errors and returns whatever it could read.

Example:

let s = from_user::single_line();
println!("raw: {:?}", s);

pub fn number() -> i32

Reads a line from stdin, validates characters, and attempts to parse the trimmed input into i32.

• On parse failure, it prints a message and retries by calling number() again.
• Intended behavior: keep asking until a valid integer is entered, then return it.

Example:

let n = from_user::number();
println!("got int: {}", n);

Known issues & quick fixes

This crate is simple by design and the current number() implementation has a few rough edges. Below are short, easy-to-understand fixes you can apply as tiny edits.

1. Loop condition is reversed — causes the loop not to run at all.

- while loop_variable > word_length {
+ while loop_variable < word_length {

2. Character check logic is inverted.

• Current code treats digits as invalid. Fix by negating the check.

- if char_to_check.is_ascii_digit() {
-     println!("Please enter a Numerics only");
-     return number();
- }
+ if !char_to_check.is_ascii_digit() {
+     println!("Please enter numerics only");
+     return number();
+ }

3. loop_variable never increments → infinite loop.

Add this at the end of the loop body:

+ loop_variable += 1;

4. chars().nth() can return None (out of bounds).

• Your code used .expect(SRS) which will panic if something goes wrong. The fixes above (loop condition and increment) avoid the out-of-bounds case. If you prefer safer code, use pattern matching on the Option<char>.

5. Parsing fallback (already present) — retry on parse error.

• The crate currently uses a match on parse() and calls number() again on Err(_) — that is fine for simplicity. Be aware that heavy recursion on many bad inputs could grow the call stack; for interactive use this is usually not a problem.

Design notes

• The crate is intentionally simple: it focuses on blocking stdin reads and straightforward retries.
• It uses recursion for retry behavior because it is easy to follow. If you plan to ship to many users or expect adversarial input, consider replacing recursion with a loop to avoid stack growth.

Contributing

• Open an issue or a pull request if you want to improve the validation, add non-blocking variants, or add tests.
• If you submit fixes, please keep changes small and document them in the PR description.

License & author

From your Cargo.toml:

• Author: Devanshu Sharma sharma.devanshu089@gmail.com
• License: MIT OR Apache-2.0