Simple code snippet Performance Test-test the Regular Expression and abnormal performance by the way (use cyclic testing for comparison)

Yesterday, in the group. some people have discussed that regular expressions are good and can be verified to avoid abnormal performance loss. as a result, we will talk about this topic. some people say that regular expressions consume a lot of energy. some people say that abnormal energy consumption is not much...

I conducted a test based on my point of view that I didn't have the right to speak. The results are as follows:

Unit (MS)	First compilation	Second	Third time	Fourth	Fifth	Recompile
regular expression test	0	0	0	0	0	0
exception test	43	23	20	15	17	41
cyclic test 0.1 million times	0	0	0	0	0	0
cyclic test 1 million times	3	3	3	3	3	3
Cyclic Testing  10 million times	33	33	33	33	33	34

 

Explanation:

During the first compilation, the exception takes a lot of time, the cycle 0.1 million times takes 0 ms, and the cycle 1 million times is 3 ms. Each refresh is fixed and remains unchanged.

The second exception ~ The fifth time (not re-compiled). There are changes to the refresh, which lingers around 15 ~ Between 27ms, while regular expressions are always stable for 0 ms.

To sum up, the exception takes a lot of time... (compared with the loop test, you can know)

 

The following are the testsCodeFragment:

Public partial class regextest: system. web. UI. page {private const string test_data = "2009-02-40"; protected void page_load (Object sender, eventargs e) {testregex (); testtrycatch (); testwhile ();} private void testwhile () {stopwatch Sw = new stopwatch (); Sw. start (); For (INT I = 0; I <10000000; I ++) {} SW. stop (); label1.text + = "loop 10000000 test:" + SW. elapsedmilliseconds + "Ms" + "<br/>";} p Rivate void testregex () {stopwatch Sw = new stopwatch (); Sw. start (); bool isdate = RegEx. ismatch (test_data, @ "^ (1 [6-9] | [2-9] \ D) \ D {2})-(0? [1, 13578] | 1 [02])-(0? [1-9] | [12] \ d | 3 [01]) | (1 [6-9] | [2-9] \ D) \ D {2})-(0? [13456789] | 1 [012])-(0? [1-9] | [12] \ d | 30) | (1 [6-9] | [2-9] \ D) \ D {2 }) -0? 2-(0? [1-9] | 1 \ d | 2 [0-9]) | (1 [6-9] | [2-9] \ D) (0 [48] | [2468] [048] | [13579] [26]) | (16 | [2468] [048] | [3579] [26]) 00)-0? 2-29-) $ "); label1.text + =" regular expression: "+ (isdate = true? "Date data": "non-date data") + "<br/>"; Sw. stop (); label1.text + = "Regular Expression test:" + SW. elapsedmilliseconds + "Ms" + "<br/>";} private void testtrycatch () {stopwatch Sw = new stopwatch (); Sw. start (); try {datetime n = convert. todatetime (test_data); label1.text + = "exception judgment: Date data <br/>";} catch {label1.text + = "exception judgment: non-date data <br/> ";} SW. stop (); label1.text + = "exception test:" + SW. elapsedmilliseconds + "Ms" + "<br/> ";}}