How to parse BigInt from the num crate? <p>I am trying to use <a href="http://rust-num.github.io/num/num/bigint/struct.BigInt.html" rel="nofollow"><code>BigInt</code></a>. My code is like this:</p> <pre><code>extern crate num; use num::bigint::BigInt; ... println!("{}", from_str::&lt;BigInt&gt;("1")); //this is line 91 in the code </code></pre> <p>In my Cargo.toml file I have the following:</p> <pre><code>[dependencies] num = "0.1.30" </code></pre> <p>What I did seem to match what was said in <a href="http://rust-num.github.io/num/num/bigint/struct.BigInt.html#method.from_bytes_be" rel="nofollow">this document</a>, <a href="http://docs.piston.rs/conrod/num/bigint/struct.BigInt.html" rel="nofollow">also this document</a> and also <a href="http://stackoverflow.com/questions/23391440/in-rust-how-do-i-use-implemented-trait-fromstr-on-bigint">an answer here on Stack Overflow</a>.</p> <p>However I got the following error:</p> <pre><code>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::&lt;BigInt&gt;("1")); </code></pre>