Using .Split to Split a string and return first integer values-CodePudding

Been trying to take a string and split it using a space and get the first integer from the string. The integer has to be on its own, so no other characters in it. Any help appreciated

CodePudding user response：

Maybe

string input = "sdf fg gfh 4v 345gg g 4 dfg dfg";

int? result  = input.Split(' ')
   .Select(x => int.TryParse(x, out int val) ? val : (int?)null)
   .FirstOrDefault(x => x != null);

Console.WriteLine(result);

Output

CodePudding user response：

Try this:

var firstOrDefaultInteger = input.Split(' ')
    .FirstOrDefault(x => int.TryParse(x, out _));

CodePudding user response：

You can try Linq in order to query the source string:

 string source = "abc a5 123 789 pqr";

 string result = source
   .Split(' ')
   .FirstOrDefault(item => item.Any() && item.All(c => c >= '0' && c <= '9'));

Here we split source into

 {"abc", "a5", "123", "789", "pqr"}

and then get "123" - first not empty item which contains digits only.

Edit: Note, that, result is of type string, since not any sequence of digits is a valid int: e.g. 123456789123456789 is too long for int. If we can guarantee that result is short enough, then you can parse it into some itenteger type, e.g.

int answer = int.Parse(result);

long answer = long.Parse(result);

or even

BigInteger answer = BigInteger.Parse(result);

If we accept negative values as well, we can put regular expression:

using System.Text.RegularExpressions;

...

string result = source
  .Split(' ')
  .FirstOrDefault(item => Regex.IsMatch(item, @"^\-?[0-9] $"));