Find and Extract a Number from a String

Find and extract a number from a string

go through the string and use Char.IsDigit

string a = "str123";
string b = string.Empty;
int val;

for (int i=0; i< a.Length; i++)
{
    if (Char.IsDigit(a[i]))
        b += a[i];
}

if (b.Length>0)
    val = int.Parse(b);

How to extract numbers from a string in Python?

If you only want to extract only positive integers, try the following:

>>> txt = "h3110 23 cat 444.4 rabbit 11 2 dog"
>>> [int(s) for s in txt.split() if s.isdigit()]
[23, 11, 2]

I would argue that this is better than the regex example because you don't need another module and it's more readable because you don't need to parse (and learn) the regex mini-language.

This will not recognize floats, negative integers, or integers in hexadecimal format. If you can't accept these limitations, jmnas's answer below will do the trick.

How can I extract a number from a string in JavaScript?

For this specific example,

 var thenum = thestring.replace( /^\D+/g, ''); // replace all leading non-digits with nothing

in the general case:

 thenum = "foo3bar5".match(/\d+/)[0] // "3"

Since this answer gained popularity for some reason, here's a bonus: regex generator.

function getre(str, num) {  if(str === num) return 'nice try';  var res = [/^\D+/g,/\D+$/g,/^\D+|\D+$/g,/\D+/g,/\D.*/g, /.*\D/g,/^\D+|\D.*$/g,/.*\D(?=\d)|\D+$/g];  for(var i = 0; i < res.length; i++)    if(str.replace(res[i], '') === num)       return 'num = str.replace(/' + res[i].source + '/g, "")';  return 'no idea';};function update() {  $ = function(x) { return document.getElementById(x) };  var re = getre($('str').value, $('num').value);  $('re').innerHTML = 'Numex speaks: <code>' + re + '</code>';}

<p>Hi, I'm Numex, the Number Extractor Oracle.<p>What is your string? <input id="str" value="42abc"></p><p>What number do you want to extract? <input id="num" value="42"></p><p><button onclick="update()">Insert Coin</button></p><p id="re"></p>

Extract digits from string - StringUtils Java

Use this code numberOnly will contain your desired output.

   String str="sdfvsdf68fsdfsf8999fsdf09";
   String numberOnly= str.replaceAll("[^0-9]", "");

Extracting numbers from vectors of strings

How about

# pattern is by finding a set of numbers in the start and capturing them
as.numeric(gsub("([0-9]+).*$", "\\1", years))

# pattern is to just remove _years_old
as.numeric(gsub(" years old", "", years))

# split by space, get the element in first index
as.numeric(sapply(strsplit(years, " "), "[[", 1))

Is there a better way to extract numbers from a string in python 3

Here's one way you can do the regex search that @Barmar suggested:

>>> import re
>>> int(re.search("\d+", "V70N-HN")[0])
70

Extract digits from a string in Java

You can use regex and delete non-digits.

str = str.replaceAll("\\D+","");

C: extract numbers from a string

You could try something like this:

Walk the string until you find the first digit (use isdigit)
Use strtoul to extract the number starting at that position
- strtoul returns the number
- the second argument (endptr) points to the next character in the string, following the extracted number
Rinse, repeat

Alternatively you could tokenize the string (using "(,+)") and try to strtoul everything.

Extract Number from String in Python

You can filter the string by digits using str.isdigit method,

>>> int(filter(str.isdigit, str1))
3158

Find and Extract a Number from a String