Replacing Text in File

Question

I wrote a method that will go through all text files, replace text, and update a textbox with said changes. It works after I run it a first time, but subsequent executions seem to infer that the files weren't changed the first time.

private void changeText(string searchString, string newString, FileInfo[] listOfFiles)
{
    foreach (FileInfo tempfi in listOfFiles)//Foreach File
    {
        string fileToBeEdited = tempfi.FullName;
        File.SetAttributes(fileToBeEdited, File.GetAttributes(fileToBeEdited) & ~FileAttributes.ReadOnly); //Remove ReadOnly Property
        string strFile = System.IO.File.ReadAllText(fileToBeEdited); //Reads In Text File
        if(strFile.Contains(newString))//If the replacement string is contained in the text file
        {
            strFile = strFile.Replace(searchString, newString);
            System.IO.File.WriteAllText(fileToBeEdited, strFile); //Write changes to File
            myTextBox.Text = "File Changed: " + fileTobeEdited.ToString() + Environment.NewLine; //Notify User
        }
    }
}

If I run this 1 time or 100 times my text files are updated just fine. If I run this a second time my textbox is re-updated saying that it updated the new files.

I would expect that this method wouldn't find any text to replace after running it a first time.

Answer 1

The variable fileToBeEdited was not initialized.

You have to look for files that contain searchString not newString !

private void changeText(string searchString, string newString, FileInfo[] listOfFiles)
{
    foreach (FileInfo tempfi in listOfFiles) {
        string fileToBeEdited = tempfi.FullName; // <== This line was missing
        File.SetAttributes(tempfi.FullName, File.GetAttributes(fileToBeEdited) &
                                            ~FileAttributes.ReadOnly);
        string strFile = System.IO.File.ReadAllText(fileToBeEdited);
        if (strFile.Contains(searchString)) { // <== replaced newString by searchString
            strFile = strFile.Replace(searchString, newString);
            System.IO.File.WriteAllText(fileToBeEdited, strFile);
            myTextBox.Text = "File Changed: " + fileToBeEdited.ToString() +
                             Environment.NewLine;
        }
    }
}

Answer 2

It doesn't look like you are actually changing the file. You are checking to see if a string is contained in the file and then if it is, you write that file back. You would have to do something like this:

    private void changeText(string searchString, string newString, FileInfo[] listOfFiles)
{
    foreach (FileInfo tempfi in listOfFiles)//Foreach File
    {
        File.SetAttributes(fileToBeEdited, File.GetAttributes(fileToBeEdited) & ~FileAttributes.ReadOnly); //Remove ReadOnly Property
        string strFile = System.IO.File.ReadAllText(fileToBeEdited); //Reads In Text File
        if(strFile.Contains(newString))//If the replacement string is contained in the text file
        {
            strFile = strFile.Replace(searchString,newString); // make the changes
            System.IO.File.WriteAllText(fileToBeEdited, strFile); //Write changes to File
            myTextBox.Text = "File Changed: " + fileTobeEdited.ToString() + Environment.NewLine; //Notify User
        }
    }
}

Then you will be able to actually save the changes to the file and after the first run the new file will have been written.

Answer 3

Maybe I'm misreading the code, but you appear to be missing the replace!

    string strFile = System.IO.File.ReadAllText(fileToBeEdited); //Reads In Text File
    if(strFile.Contains(searchString))//If the replacement string is contained in the text file
    {
        strFile = strFile.Replace(searchString, newString);
 ....

Also note how I check if the file contains the searchstring, not the newstring.