Text File help required in c# windows application

I am working with .txt files in C#, I want a functionality that if any text already exist in my .txt file, it should not write it.

Can somebody Please help me?

Thank you

 

Its pretty simple you can use following code for it

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
}
}