rust - Find a string starting from given index -

what correct way how find substring if need start not 0?

i have code:

fn splitfile(reader: bufreader<file>) {   line in reader.lines() {     let mut l = line.unwrap();     // l contains "06:31:53.012   index0:2015-01-06 00:00:13.084     ... 

i need find third : , parse date behind it. still no idea how it, because find doesn't have param begin - see https://doc.rust-lang.org/std/string/struct.string.html#method.find.

(i know can use regex. have done, i'd compare performance - whether parsing hand might quicker using regex.)

you right, there doesn't appear trivial way of skipping several matches when searching string. can hand though.

fn split_file(reader: bufreader<file>) {     line in reader.lines() {         let mut l = &line.as_ref().unwrap()[..]; // slice         _ in 0..3 {             if let some(idx) = l.find(":") {                 l = &l[idx+1..]             } else {                 panic!("the line didn't have enough colons"); // shouldn't panic             }         }         // l contains date         ... 

update:

as faiface points out below, can bit cleaner splitn():

fn split_file(reader: bufreader<file>) {     line in reader.lines() {         let l = line.unwrap();         if let some(datetime) = l.splitn(4, ':').last() {             // datetime contains timestamp string             ...         } else {             panic!("line doesn't contain timestamp");         }     } } 

you should go upvote answer.