Speed of VB.net Regex? -

is regex code in vb.net known slow?

i took on code cleaning large amounts of text data. code ran slow, looking ways speed up. found couple functions got run lot thought might part of problem.

here's original code cleaning phone number:

        dim strarray() char = strphonenum.tochararray         dim strnewphone string = ""         dim integer          = 0 strarray.length - 1             if strarray.length = 11 , strarray(0) = "1" , = 0                 continue             end if              if isnumeric(strarray(i))                 strnewphone = strnewphone & strarray(i)             end if         next          if len(strnewphone) = 7 or len(strnewphone) = 10             return strnewphone         end if 

i rewrote code eliminate array , looping using regex.

        dim strnewphone string = ""         strnewphone = regex.replace(strphonenum, "\d", "")         if strnewphone = "" orelse strnewphone.substring(0, 1) <> "1"             return strnewphone         else             strnewphone = mid(strnewphone, 2)         end if          if len(strnewphone) = 7 or len(strnewphone) = 10             return strnewphone         end if 

after running couple tests, new code slower old. regex in vb.net slow, did add other thing issue, or original code fine way was?

i conducted tests visual studio profiler , did not same results did. there logical error regex function caused length check missed if number didn't begin 1. corrected in tests.

1. i realized in tests, whatever function went first , last suffer penalty. executed each function independently , had priming function run before.
2. depending on tests executed function either 10000 or 100000 times phone number pattern of varying length. each method got same numbers.

results

in general method faster.

1. i did cheap timer test, original function twice slow.
2. profiler showed original method used 60% more memory our methods.
3. profiler showed original method took 8 times long work.
4. profiler showed original method took 40% more processor cycles.

my conclusion

in tests original method slower. had come out better in 1 test able explain our discrepancy. ff tested methods in total isolation think come similar.

my best guess else effecting results , assessment original method better false.

your revised function

function getphonenumberregex(strphonenum string)     dim strnewphone string = ""     strnewphone = regex.replace(strphonenum, "\d", "")     if strnewphone <> "" , strnewphone.substring(0, 1) = "1"         strnewphone = mid(strnewphone, 2)     end if      if len(strnewphone) = 7 or len(strnewphone) = 10         return strnewphone     end if      return "" end function 

my function

function getphonenumbermine(strphonenum string)     dim strnewphone string = regex.replace(strphonenum, "\d", "")     if (strnewphone.length >= 7 , strnewphone(0) = "1")         strnewphone = strnewphone.remove(0, 1)     end if      return if(strnewphone.length = 7 orelse strnewphone.length = 10, strnewphone, "") end function