check if string exists in a file

Question

I have the following piece of code which opens a text file and reads all the lines in the file and storing it into a string array.

Which then checks if

Answer 1

Simplest way:

string content = File.ReadAllText(path);
if (content.IndexOf(domain) > -1)
{
   // domain exists
}
else
{
   // domain does not exist
}

and now to analyze your code:

1st, you are creating StreamReader instance, but you don't use it later in your code.

2nd, what if domain name has multiple occurrence in the file? In your code you will get multiple 'there is a match' in your code.

using (StreamReader sr = File.OpenText(path)) // you can remove this line
{
    string[] lines = File.ReadAllLines(path); // as you are not using it here
    for (int x = 0; x < lines.Length - 1; x++)
    {
        if (domain == lines[x])
        {
            sr.Close();
            MessageBox.Show("there is a match");
            hasMatch = true;
            break; // exit loop if found
        }
    }

    if (!hasMatch)
    {
        // there is no match
    }

    if (sr != null) // you dont need this if you remove it from the beginning of the code
    {
        sr.Close();
        MessageBox.Show("there is no match");
    }
}