Error Cannot implicitly convert type 'string[]' to 'string'

Question

I am experiencing an Error within nouns[i] = SearchKeywords(words, sentences); every time I run my program. What should I do?

*I edited to include the SearchKeywords method. I am trying to find all words that have "a" and "an" before them.

Error is, Error Cannot implicitly convert type 'string[]' to 'string'

    string[] SearchKeywords(List<string> keywords, string[] sentence){

    int[] location = new int[sentence.Length];

    foreach (string word in keywords)
    {
        for (int i = 0; i < sentence.Length;i++ )
        {
            string[] nouns = new string[i];
            if (String.IsNullOrEmpty(sentence[i]))
            {
                return null;
            }
            else
            {
                location[i] = sentence[i].IndexOf(word);

                nouns[i] = sentence[i].Substring(location[i]);

                if (nouns[i].Contains(word)) return nouns;
            }
        }

    }
    return sentence;

   string[] checkForIndefinite()
   {
       string input = txtEntry.Text;

       string text = lbltxtOutput.Text;

       Tools tool = new Tools();    

       List<string> words = new List<string>();
       words.Add("an");
       words.Add("a");

       foreach(string sentence in GetWords(text))
       {
           for (int i = 0; i < sentence.Length; i++)
           {
               string[] nouns = new string[i];
               string[] sentences = new string[i];
               sentences[i] = sentence;

               **nouns[i] = SearchKeywords(words, sentences);**

              return nouns;

           }
       }
       return null;
   }

What Type does SearchKeywords method return? I assume string[]? — ToddB
– ToddB, Commented May 21, 2015 at 2:30
SearchKeywords is returning an array of strings, which you are trying to assign to a (single) string variable. Obviously, you can't do that. It can't really be fixed without knowing what your goal for this code is. — Blorgbeard
– Blorgbeard, Commented May 21, 2015 at 2:33
I edited to include the SearchKeywords method. I am trying to find all words that have "a" and "an" before them. — Ivan
– Ivan, Commented May 21, 2015 at 2:42

Enigmativity · Accepted Answer · 2015-05-21 22:42:18Z

2

It seems to me that this is what you need:

string[] SearchKeywords(List<string> keywords, string[] sentence)
{
    return
        sentence
            .Zip(sentence.Skip(1), (w0, w1) => new { w0, w1 })
            .Where(ww => keywords.Contains(ww.w0))
            .Select(ww => ww.w1)
            .ToArray();
}

string[] checkForIndefinite()
{
    var input = txtEntry.Text;
    var text = lbltxtOutput.Text;
    var words = new List<string>() { "an", "a" };
    return SearchKeywords(words, GetWords(text));
}

edited May 21, 2015 at 22:42

answered May 21, 2015 at 2:52

Enigmativity

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6 Comments

John Hodge Over a year ago

This is giving me an error on line .Where(ww => keywords.Contains(w0)) saying that, "The name w0 does not exist in the current context."

Enigmativity Over a year ago

Have you got using System.Linq; at the top?

Enigmativity Over a year ago

@JohnHodge - It worked just fine for me. I run every answer in LINQPad before posting.

John Hodge Over a year ago

I have using System.Linq;. Here the entire program if you want to take a look: https://dotnetfiddle.net/KL8QeX

John Hodge Over a year ago

For what it's worth, I get the same result in Visual Studio.

|

Hossein Narimani Rad · Accepted Answer · 2015-05-21 02:53:54Z

0

The output of the SearchKeywords function is an string[] and the nouns[i] is a string and simply you cannot assign and string[] value to a string. So You may what to try something like this:

List<string> nouns = new List<string>();

//foreach loop
    //    for loop

        nouns.AddRange(SearchKeywords(words, sentences));

answered May 21, 2015 at 2:53

Hossein Narimani Rad

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Comments

John Hodge · Accepted Answer · 2015-05-21 03:02:25Z

using System;
using System.Security.Cryptography;
using System.Text;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        string[] indefinites = checkForIndefinite();
        foreach (string s in indefinites)
        {
            Console.WriteLine(s);
        }
    }


    static string[] SearchKeywords(List<string> keywords, string sentence)
    {
        if (String.IsNullOrEmpty(sentence))
        {
            return null;
        }

        List<string> nouns = new List<string>();

        string[] words = sentence.Split(' ');

        foreach (string keyword in keywords)
        {
            for (int i = 0; i < words.Length; i++ )
            {
                if (words[i] == keyword)
                {
                    if (i+1 < words.Length && !nouns.Contains(words[i+1]))
                    {
                        nouns.Add(words[i+1]);
                    }
                }
            }
        }
        return nouns.ToArray();
    }

   static string[] checkForIndefinite()
   {
       string sentence = "This is not an interesting sentence to use to test a program";

       string text = string.Empty;   

       List<string> words = new List<string>();
       words.Add("an");
       words.Add("a");

       return SearchKeywords(words, sentence);

   }
}

This compiles and returns the following:

interesting
program

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