Question

I am trying to write a program that can replace text and replace also Regex text.
So I am having trouble with the regex replace part..I’m a real noob 🙂

private void button2_Click(object sender, EventArgs e)
{
    if (File.Exists(textBox1.Text))
    {

//this is the regular replace:

        if (checkBox1.Checked == false)
        {
            StreamReader sr = new StreamReader(textBox1.Text);
            StreamWriter sw = new StreamWriter(textBox1.Text.Replace(".", "_new."));
            string cur = "";
            do
            {
                cur = sr.ReadLine();
                cur = cur.Replace(textBox2.Text, textBox3.Text);
                sw.WriteLine(cur);
            }
            while (!sr.EndOfStream);

            sw.Close();
            sr.Close();

            MessageBox.Show("Finished, the new file is in the same directory as the old one");
        }

//this is the REGEX replace:

        if (checkBox1.Checked == true)
        {
            System.Text.RegularExpressions.Regex g = new Regex(@textBox2.Text);
            using (StreamReader r = new StreamReader(textBox1.Text))
            {
                StreamReader sr = new StreamReader(textBox1.Text);
                StreamWriter sw = new StreamWriter(textBox1.Text.Replace(".", "_new."));
                string cur = "";
                do
                {
                    cur = sr.ReadLine();
                    cur = cur.Replace(textBox2.Text, textBox3.Text);
                    sw.WriteLine(cur);
                }
                while (!sr.EndOfStream);

                sw.Close();
                sr.Close();

            }
            MessageBox.Show("Finished, the new file is in the same directory as the old one");
        }


        button2.Enabled = false;
    }
    if (File.Exists(textBox1.Text) == false)
    {
    MessageBox.Show("Please select a file and try again.");

    }
}

Answer 1

The Regex replace function can be found in the MSDN Regular Expression Replace documentation.

Use: Regex.Replace(input, pattern, replacement);

string inputFilename = textBox1.Text;
string outputFilename = inputFilename.Replace(".", "_new.");
string regexPattern = textBox2.Text;
string replaceText = textBox3.Text;

using (StreamWriter sw = new StreamWriter(outputFilename)))
{
    foreach (string line in File.ReadAllLines(inputFilename))
    {
        string newLine = Regex.Replace(line, regexPattern, replaceText);
        sw.WriteLine(newLine);
    }
}