Searching an Array using a while loop in C#?

Question

I'm trying to use a while loop to search an array, using a users search input, at the minute I have listed one word film titles into a standard text file, and then the while loop keeps searching the file until it is found, and then it is output on the console.. But I have the problem that the operator "==" can't be applied to string variables? How would I fix this? Thanks a lot! And merry Christmas, here Is my code:

        //Declare variables
        int iOneWordTitle= 0;
        string sSearch;

        //Declare array
        const int iFilm = 7;
        string[] sOneWordTitle = new string[iFilm];

        //Add heading to console
        Console.WriteLine("List of one word film titles");
        Console.WriteLine();

        //ask user what they want to search for
        Console.WriteLine("What film would you like to search for?");
        sSearch = Console.ReadLine();

        //Read the film names from the datafile
        using (StreamReader sr = new StreamReader("filmnames.txt"))
        {
            while (iOneWordTitle < iFilm)
            {
                sOneWordTitle[iOneWordTitle] = (sr.ReadLine());
                iOneWordTitle++;

                if (sSearch == sOneWordTitle)
                {
                    Console.WriteLine(sSearch + " was found at position " + iOneWordTitle);
                }

                else
                {
                    Console.WriteLine("The film was not found");
                }
            }

        }

if (sSearch == sOneWordTitle) compares a string to a string[]. You may want to figure out what you really want to compare there. — Joachim Isaksson
– Joachim Isaksson, Commented Dec 21, 2013 at 18:38
I want it so that if the search is equal to the film, then to output it on the console — Tom
– Tom, Commented Dec 21, 2013 at 18:40
By doing this, you are comparing the string against the array object, not the strings contained within the array. — Chris W
– Chris W, Commented Dec 21, 2013 at 18:42

Liel · Accepted Answer · 2013-12-21 19:17:13Z

2

Instead of using StreamReader, you can easily read all the lines in a text file using File.ReadAllLines()
You are also printing The film was not found 7 times. If you prefer to print it only once, you can keep a bool variable to indicate it wasn't found.
you pre-configured the number of titles in the file to be 7. What if there can be more titles in the file?

So, I think you might want to change your code a little:

        int iOneWordTitle = 0;
        string sSearch;

        //Add heading to console
        Console.WriteLine("List of one word film titles");
        Console.WriteLine();

        //ask user what they want to search for
        Console.WriteLine("What film would you like to search for?");
        sSearch = Console.ReadLine();

        //Read all titles from the text file
        string[] titles = File.ReadAllLines("filmnames.txt");

        //Search the array
        bool found = false;
        foreach (string title in titles)
        {
            if (title.Equals(sSearch))
            {
                Console.WriteLine(sSearch + " was found");
                found = true;
            }
        }

        //If the title wasn't found, print not found message
        if (!found)
            Console.WriteLine("The film was not found");

if you still want to print position it was found on, you can convert your foreach loop to a regular loop:

        for (int iOneWordTitle = 0; iOneWordTitle < titles.Count(); iOneWordTitle++)
        {
            if (titles[iOneWordTitle].Equals(sSearch))
            {
                Console.WriteLine(sSearch + " was found at position " + iOneWordTitle);
                found = true;
            }
        }

edited Dec 21, 2013 at 19:17

answered Dec 21, 2013 at 18:44

Liel

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1 Comment

Tom Over a year ago

Thanks, the first method seems to work great for finding the film, I'm a little confused though how I would implement this for loop into it to find the position of the film on the list, could you provide any further help? Thanks :)

Baldrick · Accepted Answer · 2013-12-21 18:42:10Z

2

It should be

if (sSearch == sOneWordTitle[iOneWordTitle])

instead of

if (sSearch == sOneWordTitle)

In your version you are comparing a string with a string array rather than the array index value.

I'd probably also give thought to your variable names.

edited Dec 21, 2013 at 18:42

Baldrick

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answered Dec 21, 2013 at 18:40

Steve

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3 Comments

Joachim Isaksson Over a year ago

The iOneWordTitle++; would need to be moved below the comparison, or the comparison will be done to the next (so far unset) array slot.

Tom Over a year ago

Yeah that kind of solves it, but Now it's just saying the film was not found when I type in a correct film name, any idea where I may have gone wrong? Thanks

Chris W Over a year ago

Try comparing the strings as lowercase or use String.Equals and StringComparison.CurrentCultureIgnoreCase

edno70 · Accepted Answer · 2013-12-21 18:42:21Z

2

It needs to be something like this:

if (sSearch == sOneWordTitle[iOneWordTitle])

Instead of doing it like this here:

 if (sSearch == sOneWordTitle)

answered Dec 21, 2013 at 18:42

edno70

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