为什么string.Replace无法正常工作？

Question

I am writing c# code to replace certain words from a file. The 2 line demo simple code that I have written is not working. There is no error and Console.WriteLine is also giving correct output.

string strFileContent = File.ReadAllText(@"C:\Users\toshal\Documents\TCS\stop_words.txt");
Console.WriteLine("strfilecontent" + strFileContent);
strFileContent = strFileContent.Replace("actually" , " ");

The string "actually" is not getting replaced in the file. What can be the problem here?

Answer 1

Ofcourse it's not getting replaced in the file, as you only read the data and then alter it.

You`ll have to write it back to the file if want to apply the changes.

string strFileContent = File.ReadAllText(@"C:\Users\toshal\Documents\TCS\stop_words.txt");
Console.WriteLine("strfilecontent" + strFileContent);
strFileContent = strFileContent.Replace("actually" , " ");

StreamWriter SW = File.CreateText(@"C:\Users\toshal\Documents\TCS\stop_words.txt");
SW.Write(strFileContent);
SW.Close();

Answer 2

You are creating a string with the replaced value, but you are never writing that value back to the file. Therefore, the file remains unchanged.

To fix, add the following line to write the changed value back to the file:

string path = @"C:\Users\toshal\Documents\TCS\stop_words.txt";
string strFileContent = File.ReadAllText(path);
Console.WriteLine("strfilecontent" + strFileContent);
strFileContent = strFileContent.Replace("actually" , " ");
File.WriteAllText(path, strFileContent);