Regular expression to match a string of arbitrary length made up of an arbitrary number of words whose last word is always Child(integer from 1 to 10)

Question

I am looking for a regular expression that would allow me filter a list of strings made of an arbitrary number of words whose last character of the last word must be less than or equal to a given integer. The last word of each of the target strings in the list is always Child<1 to 10>. For example:

List<string> attributes = new List<string>
{
     "First Name of Child1",
     "Last Name of Child1",
     "Age of Child1",
     "Shipping Instructions",
     "First Name of Child2",
     "Last Name of Child2",
     "Age of Child2",
     "Non-Profit Name",
     "First Name of Child3",
     "Last Name of Child3",
     "Age of Child3",
}

If the target integer is 2, the filtered list would contain:

 "First Name of Child1",
 "Last Name of Child1",
 "Age of Child1",
 "First Name of Child2",
 "Last Name of Child2",
 "Age of Child2"

Might be best to use a combination of RegEx and Linq for this. With RegEx, look for any string that ends with numeric digits and return those as a group. With Linq, convert that group to an int and filter out anything greater than your target integer. — Mike Christensen, Oct 19 '15 at 22:20

score 1 · Answer 1 · answered Oct 19 '15 at 22:29

1

var regex=new Regex(string.Join("|",Enumerable.Range(0,n).Select(i=>"Child"+i+"$")));

answered Oct 19 '15 at 22:29

Blindy

65,249
10
91
131

Luc Morin · Answer 2 · 2015-10-19T23:35:25.433

0

Try this:

int selected = 2;
string exp = "Child(?<number>\\d{1,2})$";
Regex rg = new Regex(exp);

var result = attributes.Where(a =>
{
    int i;
    string target = rg.Match(a).Groups["number"].Value;
    if (!int.TryParse(target, out i))
        return false;
    return (i <= selected);

});

Code edited because of my poor understanding of regular expression numeric "range" handling.

edited Oct 19 '15 at 23:35

answered Oct 19 '15 at 22:32

Luc Morin

5,302
20
39

This wouldn't match `Child1` – Mike Christensen Oct 19 '15 at 22:34
Just change `selected` to be 1 – Luc Morin Oct 19 '15 at 22:35
Then it wouldn't match `Child2` – Mike Christensen Oct 19 '15 at 22:35
Let me re-read the question, I may have misunderstood something – Luc Morin Oct 19 '15 at 22:35
They want to return every value *below* a certain target number. The answer below should work. – Mike Christensen Oct 19 '15 at 22:36
Please check http://stackoverflow.com/questions/1377926/regular-expression-numeric-range - your C# 6 -only sample will not handle "Child10". – Alexei Levenkov Oct 19 '15 at 23:03
I see. I will delete my answer. One question to you though. Your comment almost makes it sound like using a "C# 6 -only" sample is bad. Anything you'd care to elaborate ? The fact that the regex won't work for 2 digits has nothing to do with C# 6 features, so I'm trying to catch the full extent of your comment. – Luc Morin Oct 19 '15 at 23:10

Regular expression to match a string of arbitrary length made up of an arbitrary number of words whose last word is always Child(integer from 1 to 10)

2 Answers2