How to parse BigInt from the num crate?

Question

I am trying to use BigInt. My code is like this:

extern crate num;
use num::bigint::BigInt;
...
println!("{}", from_str::<BigInt>("1")); //this is line 91 in the code

In my Cargo.toml file I have the following:

[dependencies]
num = "0.1.30"

What I did seem to match what was said in this document, also this document and also an answer here on Stack Overflow.

However I got the following error:

Compiling example v0.1.0 (file:///C:/src/rust/example)
src\main.rs:91:20: 91:38 error: unresolved name `from_str` [E0425]
src\main.rs:91     println!("{}", from_str::<BigInt>("1"));

Answer 1

Figured out, seem like the current syntax is:

"8705702225074732811211966512111".parse::<BigInt>().unwrap();

Better yet, do the following:

match "8705702225074732811211966512111".parse::<BigInt>() {
    Ok(big) => {
        ...