C# Text file question (help)

var filename = @"c:\test.txt";
var textToWrite = "your text here";
string fileContents;


// Get File Text
using (var sr = new StreamReader(filename))
{
    fileContents = sr.ReadToEnd();
}


// Write to File
using (var sw = new StreamWriter(filename, true))
{
    // check if text already exists in file
    if (!fileContents.Contains(textToWrite))
    {
        sw.WriteLine(textToWrite); // or use sw.Write depending on the usage scenario
    }
}

var contents = File.ReadAllText(@"c:\path\file.txt");
if(!contents.Contains(strToFind)){
    File.WriteAllText(@"c:\path\file.txt", contentsToWrite);
}