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POFaster than String.Replace()
 

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    <p>Is there any other method that is faster than doing like this?</p> <pre><code>private void EscapeStringSequence(ref string data) { data = data.Replace("\\", "\\\\"); // Backslash data = data.Replace("\r", "\\r"); // Carriage return data = data.Replace("\n", "\\n"); // New Line data = data.Replace("\a", "\\a"); // Vertical tab data = data.Replace("\b", "\\b"); // Backspace data = data.Replace("\f", "\\f"); // Formfeed data = data.Replace("\t", "\\t"); // Horizontal tab data = data.Replace("\v", "\\v"); // Vertical tab data = data.Replace("\"", "\\\""); // Double quotation mark data = data.Replace("'", "\\'"); // Single quotation mark } </code></pre> <p>-- Edited (Add explanation) -- <br /> <em>Q1: Is there a reason why you need to speed it up? Is it causing a huge problem?</em> <br /> This part is used in this project: <a href="http://mysqlbackuprestore.codeplex.com/" rel="nofollow">http://mysqlbackuprestore.codeplex.com/</a> <br /> I'm going to loop lots of various length of strings into this function repeatly. The whole process takes around 6-15 seconds to finished for millions of rows. There are other part get involve too. I'm trying to speed up every part.</p> <p><em>Q2: How slow is it now?</em> <br /> OK, I'll capture the exact time used and post it here. I'll come back later. (will post the result tomorrow)</p> <p><strong>Update 29-06-2012</strong><br /> Hey, guys. I have run test. This is the result:<br /> <br/> <strong>Speed Test: String.Replace()</strong> - measured in miliseconds<br/> Test 1: 26749.7531 ms<br /> Test 2: 27063.438 ms<br /> Test 3: 27753.8884 ms<br /> Average: 27189.0265 ms<br /> Speed: 100%<br/> <br /> <strong>Speed Test: Foreach Char and Append</strong> - measured in miliseconds<br /> Test 1: 8468.4547 ms<br /> Test 2: 8348.8527 ms<br /> Test 3: 8353.6476 ms<br /> Average: 8390.3183 ms<br /> <strong>Speed: 224% &lt; faster</strong><br /> ===================================<br /> <strong>Update - Next Test (Another round)</strong><br /> ===================================<br /> ------<br /> Test Replace String Speed.<br /> Test 1: 26535.6466<br /> Test 2: 26379.6464<br /> Test 3: 26379.6463<br /> Average: 26431.6464333333<br /> Speed: 100%<br /> ------<br /> Test Foreach Char String Append.<br /> Test 1: 8502.015<br /> Test 2: 8517.6149<br /> Test 3: 8595.6151<br /> Average: 8538.415<br /> Speed: 309.56%<br /> ------<br /> Test Foreach Char String Append (Fix StringBuilder Length).<br /> Test 1: 8314.8146<br /> Test 2: 8330.4147<br /> Test 3: 8346.0146<br /> Average: 8330.41463333333<br /> Speed: 317.29%<br /> <br /> <br/> Conclusion:<br/> Using Foreach Char Loop and Append is faster than String.Replace().<br /> <br /> Thanks you very much guys.<br /> <br /> --------<br /> Below are the codes that I used to run the test: (edited)<br /></p> <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Console.Write("Press any key to continue..."); Console.ReadKey(); Console.Write("\r\nProcess started."); Test(); Console.WriteLine("Done."); Console.Read(); } public static Random random = new Random((int)DateTime.Now.Ticks); public static string RandomString(int size) { StringBuilder sb = new StringBuilder(); char ch; for (int i = 0; i &lt; size; i++) { ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65))); sb.Append(ch); } return sb.ToString(); } public static void Test() { string text = "\\_\r\n\a\b\f\t\v\"'" + RandomString(2000) + "\\_\r\n\a\b\f\t\v\"'" + RandomString(2000); List&lt;TimeSpan&gt; lstTimeUsed = new List&lt;TimeSpan&gt;(); int target = 100000; for (int i = 0; i &lt; 3; i++) { DateTime startTime = DateTime.Now; for (int j = 0; j &lt; target; j++) { if (j.ToString().EndsWith("000")) { Console.Clear(); Console.WriteLine("Test " + i.ToString()); Console.WriteLine(j.ToString() + " of " + target.ToString()); } string data = text; data = data.Replace("\\", "\\\\"); // Backslash data = data.Replace("\r", "\\r"); // Carriage return data = data.Replace("\n", "\\n"); // New Line data = data.Replace("\a", "\\a"); // Vertical tab data = data.Replace("\b", "\\b"); // Backspace data = data.Replace("\f", "\\f"); // Formfeed data = data.Replace("\t", "\\t"); // Horizontal tab data = data.Replace("\v", "\\v"); // Vertical tab data = data.Replace("\"", "\\\""); // Double quotation mark data = data.Replace("'", "\\'"); // Single quotation mark } DateTime endTime = DateTime.Now; TimeSpan ts = endTime - startTime; lstTimeUsed.Add(ts); } double t1 = lstTimeUsed[0].TotalMilliseconds; double t2 = lstTimeUsed[1].TotalMilliseconds; double t3 = lstTimeUsed[2].TotalMilliseconds; double tOri = (t1 + t2 + t3) / 3; System.IO.TextWriter tw = new System.IO.StreamWriter("D:\\test.txt", true); tw.WriteLine("------"); tw.WriteLine("Test Replace String Speed. Test Time: " + DateTime.Now.ToString()); tw.WriteLine("Test 1: " + t1.ToString()); tw.WriteLine("Test 2: " + t2.ToString()); tw.WriteLine("Test 3: " + t3.ToString()); tw.WriteLine("Average: " + tOri.ToString()); tw.WriteLine("Speed: 100%"); tw.Close(); lstTimeUsed = new List&lt;TimeSpan&gt;(); for (int i = 0; i &lt; 3; i++) { DateTime startTime = DateTime.Now; for (int j = 0; j &lt; target; j++) { if (j.ToString().EndsWith("000")) { Console.Clear(); Console.WriteLine("Test " + i.ToString()); Console.WriteLine(j.ToString() + " of " + target.ToString()); } string data = text; var builder = new StringBuilder(); foreach (var ch in data) { switch (ch) { case '\\': case '\r': case '\n': case '\a': case '\b': case '\f': case '\t': case '\v': case '\"': case '\'': builder.Append('\\'); break; default: break; } builder.Append(ch); } } DateTime endTime = DateTime.Now; TimeSpan ts = endTime - startTime; lstTimeUsed.Add(ts); } t1 = lstTimeUsed[0].TotalMilliseconds; t2 = lstTimeUsed[1].TotalMilliseconds; t3 = lstTimeUsed[2].TotalMilliseconds; tw = new System.IO.StreamWriter("D:\\test.txt", true); tw.WriteLine("------"); tw.WriteLine("Test Foreach Char String Append. Test Time: " + DateTime.Now.ToString()); tw.WriteLine("Test 1: " + t1.ToString()); tw.WriteLine("Test 2: " + t2.ToString()); tw.WriteLine("Test 3: " + t3.ToString()); tw.WriteLine("Average: " + ((t1 + t2 + t3) / 3).ToString()); tw.WriteLine("Speed: " + ((tOri) / ((t1 + t2 + t3) / 3) * 100).ToString("0.00") + "%"); tw.Close(); lstTimeUsed = new List&lt;TimeSpan&gt;(); for (int i = 0; i &lt; 3; i++) { DateTime startTime = DateTime.Now; for (int j = 0; j &lt; target; j++) { if (j.ToString().EndsWith("000")) { Console.Clear(); Console.WriteLine("Test " + i.ToString()); Console.WriteLine(j.ToString() + " of " + target.ToString()); } string data = text; var builder = new StringBuilder(data.Length + 20); foreach (var ch in data) { switch (ch) { case '\\': case '\r': case '\n': case '\a': case '\b': case '\f': case '\t': case '\v': case '\"': case '\'': builder.Append('\\'); break; default: break; } builder.Append(ch); } } DateTime endTime = DateTime.Now; TimeSpan ts = endTime - startTime; lstTimeUsed.Add(ts); } t1 = lstTimeUsed[0].TotalMilliseconds; t2 = lstTimeUsed[1].TotalMilliseconds; t3 = lstTimeUsed[2].TotalMilliseconds; tw = new System.IO.StreamWriter("D:\\test.txt", true); tw.WriteLine("------"); tw.WriteLine("Test Foreach Char String Append (Fix StringBuilder Length). Test Time: " + DateTime.Now.ToString()); tw.WriteLine("Test 1: " + t1.ToString()); tw.WriteLine("Test 2: " + t2.ToString()); tw.WriteLine("Test 3: " + t3.ToString()); tw.WriteLine("Average: " + ((t1 + t2 + t3) / 3).ToString()); tw.WriteLine("Speed: " + ((tOri) / ((t1 + t2 + t3) / 3) * 100).ToString("0.00") + "%"); tw.Close(); } } } </code></pre>
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    1. COHow slow is it now?
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    2. COpossible duplicate of [fastest way to replace string in a template](http://stackoverflow.com/questions/959940/fastest-way-to-replace-string-in-a-template)
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    3. COPutting the string into a StringBuilder and then using StringBuilder.Replace may be faster. Writing your own one-pass loop that constructs the resulting string should be much faster.
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