Improving the efficiency of C # Regular Expressions

Speaking of C #'s Regex, the most talked about should be RegexOptions. compiled: RegexOptions in terms of matching speed. compiled can improve the matching speed, but RegexOptions is used in the startup speed. compiled usually slows down the startup, which is said to be up to 60 times faster.

Conduct a group of tests and have test data before discussion.

The first step is to test the hardware information on the post (haha, the hardware is a bit bad :()

Step 2,

A. test if RegexOptions. Compiled item is not used, use some content at will, and then instantiate the regular expression object 10 thousand times in a loop to match the content.

Code

 protected void Page_Load(object sender, EventArgs e)
    {
        WebClient webClient = new WebClient();
        string content = webClient.DownloadString("http://www.cnblogs.com/tmyh/archive/2010/09/29/sqlindex_01.html");

        Stopwatch watcher = new Stopwatch();
        watcher.Start();

        int i = 10000;
        while (i > 0)
        {
            Regex rgx = new Regex("<div>.+?</div>", RegexOptions.IgnoreCase | RegexOptions.Singleline);
            bool b1 = rgx.IsMatch(content);

            Regex rgx2 = new Regex("<p>.+?</p>", RegexOptions.IgnoreCase | RegexOptions.Singleline);
            bool b2 = rgx2.IsMatch(content);

            i--;
        }
        Response.Write(string.Concat("<div>", watcher.Elapsed.TotalSeconds.ToString("f7"), "</div>"));
    }

 

The execution shows that the memory usage is 39,760 kb. The output execution time is 3.7954446 seconds (the shortest time is obtained after several clicks)

B. Test the situation when RegexOptions. Compiled item is used. Use some content at will, and then instantiate the regular expression object 10 thousand times in a loop to match the content.

Code

 protected void Page_Load(object sender, EventArgs e)
    {
        WebClient webClient = new WebClient();
        string content = webClient.DownloadString("http://www.cnblogs.com/tmyh/archive/2010/09/29/sqlindex_01.html");


Stopwatch watcher = new Stopwatch();
watcher.Start();

int i = 10000;
while (i > 0)
{
Regex rgx = new