CODEWITHSUNDEEP
c#regex
Victorgalaxy
Victorgalaxy

Reputation: 397

A simple Read-Write huge input file problem

As title, I'm trying to replace 2 or more space between characters into a single space. The following code works, however, not for very large input file. How can I make it works for huge input file as well? 

  static void Main(string[] args)
    {
        Regex pattern = new Regex(@"[ ]{2,}");   //Pattern = 2 or more space in a string.

        StreamReader reader = new StreamReader(@"C:\CSharpProject\in\abc.txt");
        string content = reader.ReadToEnd();
        reader.Close();

        content = pattern.Replace(content, @" ");   //Replace 2 or more space into a single space.
        StreamWriter writer = new StreamWriter(@"C:\CSharpProject\out\abc.txt");
        writer.Write(content);
        writer.Close();
    }

Upvotes: 1

Views: 171

Answers (2)

agent-j
agent-j

Reputation: 27923

Line-by-line, like this:

static void Main(string[] args)
{
    Regex pattern = new Regex(@"[ ]{2,}");   //Pattern = 2 or more space in a string.

    using (StreamReader reader = new StreamReader(@"C:\CSharpProject\in\abc.txt"))
    using (StreamWriter writer = new StreamWriter(@"C:\CSharpProject\out\abc.txt"))
    {
       string content;
       while (null != (content = reader.ReadLine()));
          writer.WriteLine (pattern.Replace (content, " "));

       writer.Close();
       reader.Close();
    }
}

Upvotes: 2

Jon Raynor
Jon Raynor

Reputation: 3892

The file is being read all at once. There are limits. Instead of reader.ReaderToEnd(), use reader.ReadLine() and read and process the file one line at a time. Or if the file doesn't have "lines" read the input file in chunks and save the output chunks as it is being processed.

Upvotes: 0

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