CODEWITHSUNDEEP
javascriptregex
Alvaro Silvino
Alvaro Silvino

Reputation: 9733

how retrieve two numbers in string using regex

I'm trying to retrieve the two integers (not floating numbers) from the following string:

 0 1 
 0 2 
 0 3 
 0 4 
 0 5 
 0 6 
 0 7 
 0 8 
 12 11
 10 22
 33 2
 102 149

I want to get in javasScript like:

 var line = "0 1";
 var firstInt = line.someMagic();
 var secondInt = line.someMagic();

please help. Any help will be appreciated. thanks!

EDIT

the split method can't be used.
cos sometimes the line has extra space in front or at the end of each line!

like:

var line = " 0 2 ";

that's why I needed the regex.

EDIT 2

Turns out, I don't need the regex!

thanks for the help!

Upvotes: 1

Views: 58

Answers (4)

Mulan
Mulan

Reputation: 135197

This solution will only work for positive integers

// ES5
var input = "0 1";
var matches = input.match(/\d+/g);
var a = matches[0];
var b = matches[1];
console.log(a); // 0
console.lob(b); // 1

It's a little nicer with ES6

// ES6
let input = "0 1";
let [a,b] = input.match(/\d+/g);
console.log(a); // 0
console.lob(b); // 1

That said, RegExp isn't the only way to solve this. You may have leading or trailing space, but that's a non-issue. Here's a functional approach that makes quick work of this problem for you

const isNumber = x => ! Number.isNaN(x);
const parseInteger = x => window.parseInt(x, 10);

let input = '    20   -54    ';
let [a,b] = input.split(' ').map(parseInteger).filter(isNumber);
console.log(a); // 20
console.lob(b); // -54

Also note some people are advising the use of .trim which is not really going to solve your problems here. Trim may remove extraneous whitespace at the beginning end of your string, but it's not going to remove extra spaces in between the numbers. My solution above works regardless of how many spaces are used, but if you evaluate it, you'll find that it might be improved by splitting (not matching) with a regexp

// same effect as above, but breaks the string into less parts
let [a,b] = input.split(/\s+/).map(parseInteger).filter(isNumber);

The result of this is that the map and filter operations don't have to test for as many '' (empty string) and NaN (not a number) values. However, the performance cost of using the regexp engine may not outweigh the few extra cycles used to process the empty strings one-by-one.

Upvotes: 2

user2182349
user2182349

Reputation: 9782

You can use the split method to break the string into an array:

var line = "0 1";
var pieces = line.trim().split(" ");
console.log(pieces);

If you prefer to use a regex:

var line = "0 1";
var pieces = /(\d+)\s(\d+)/g.exec(line);
console.log(pieces);

Upvotes: 1

Alex McMillan
Alex McMillan

Reputation: 17952

Just split the line on the space, and parseInt the chars into numbers :)

var line = "-21 42";

var ints = line.split(' ').map(function (num) {
    return parseInt(num, 10);
});

var firstInt = ints[0]; // -21
var secondInt = ints[1]; // 42

Edit:

If you are worried about trailing spaces etc, just trim the string first:

var ints = line.trim().split(' ').map(...

Upvotes: 4

Nick Zuber
Nick Zuber

Reputation: 5637

You don't even need regex for this, it can be done very simply:

var line = "0 1";

// Split line into an array using the space as a delimiter
var parsedLine = line.split(" ");
var firstInt = parsedLine[0]; // => 0
var secondInt = parsedLine[1]; // => 1

Upvotes: 0

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