This is my code, I am taking input from user, I want to find out the index/ or position of the longest word in the string the user is typing. I can't seem to figure this out! Wherever I try to find help, I get indexOf() method in which you manually have to type the word of which you are trying to find index.

This is my code:

using System;
using System.Linq;

public class Question1
{
public static void Main(string[] args)
{
   
    Console.WriteLine("Enter String:");
    string line = Console.ReadLine();
    string[] words = line.Split(new[] { " " }, StringSplitOptions.None);
    string word = "";
    int ctr = 0 , len, max = 0;
    
    foreach (String s in words)
    {
        if (s.Length > ctr)
        {
            word = s;
            ctr = s.Length;
           

        }

    }
    Console.WriteLine("Longest String : "   word);
    Console.WriteLine("Length : "   ctr);

}
 }

CodePudding user response：

To find longest word index from a sentence you have to use .indexOf() method from Array class.

Instead of

Console.WriteLine(word.IndexOf(word, ctr));

Try,

int longestWordIndex = Array.IndexOf(words, word);
Console.WriteLine($"Index of Longest word = {longestWordIndex}");

CodePudding user response：

You can find the index of the word you've found like this:

int indexOfWord = line.IndexOf(word, StringComparison.CurrentCulture);

So if the word is the first word, indexOfWord will be 0. If it's "William" in "Hello William", then it will be 6, etc.

Try it online

CodePudding user response：

Validation of punctuation and other characters aside:

const string sentence = "Find the position of the longest word in this sentence";

var longestWord =
   sentence
      .Split(' ')
      .OrderByDescending(w => w.Length)
      .First();

var position = sentence.IndexOf(longestWord, StringComparison.InvariantCulture);

CodePudding user response：

In general case, we should come to terms: what word is. If we agree that

Word is a non-empty sequence of letters and apostrophes

we can match words with a help of regular expessions and then query matches to obtain the longest one with a help of Linq. Please, note, that in general case (with punctuations) Split is not enough.

Code:

using System.Linq;
using System.Text.RegularExpressions;

...

string line = 
  "This is the sentence; it has some punctuations! ---note-it's-not-the-longest--";

var result = Regex
  .Matches(line, @"[\p{L}'] ")
  .Cast<Match>()
  .MaxBy(match => match.Value.Length);

Console.Write(
  $"Word is \"{result.Value}\" at postion {result.Index} (length {result.Length})"
);

Outcome:

Word is "punctuations" at postion 34 (length 12)