C#

Simon Stevens wrote:

Rather than only holding the line numbers in the array. Make it a string array*, and store the whole line in the array.

void CopyLines(string inFile, string outFile){
    StreamReader sr = new StreamReader(File.Open(inFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite));
    StreamWriter sw = new StreamWriter(outFile);
    string line;
    while (!sr.EndOfStream) {
        line = sr.ReadLine();
        if ( Match(line) ) {
            sw.WriteLine(line);
        }
        sw.Flush();
    }
    sr.Close();
    sw.Close();
}