Is there a way to write a faster function ?
public static bool IsNumber( char Value )
{
if (Regex.IsMatch( Value.ToString(), @"^[0-9]+$" ))
{
return true;
}
else return false;
}
I think, if I have to repat this some thousands time, it
could become very time consuming.
Thanks in advance,
P.S.
Is there in C# something similar to Delphi's sets ? 9 4552
Tim Conner <Ti*******@discussions.microsoft.com> wrote: Is there a way to write a faster function ?
public static bool IsNumber( char Value ) { if (Regex.IsMatch( Value.ToString(), @"^[0-9]+$" )) { return true; } else return false; }
I think, if I have to repat this some thousands time, it could become very time consuming.
While regular expressions are very powerful, they're not very fast for
doing simple thing - and you're creating a new string for each call as
well. Far simpler and faster is:
public static bool IsNumber (char value)
{
return (value>='0' && value <='9');
}
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Why don't you try the framework given method ?
Check the Char.IsNumber( ) ?
For example :
Console.WriteLine(Char.IsNumber('8')); // Output: "True"
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om... Tim Conner <Ti*******@discussions.microsoft.com> wrote: Is there a way to write a faster function ?
public static bool IsNumber( char Value ) { if (Regex.IsMatch( Value.ToString(), @"^[0-9]+$" )) { return true; } else return false; }
I think, if I have to repat this some thousands time, it could become very time consuming.
While regular expressions are very powerful, they're not very fast for doing simple thing - and you're creating a new string for each call as well. Far simpler and faster is:
public static bool IsNumber (char value) { return (value>='0' && value <='9'); }
-- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet If replying to the group, please do not mail me too
Tim,
In addition to Jon's comments.
Is there a reason you are not using the static Char.IsDigit or Char.IsNumber
function? public static bool IsNumber( char Value ) {
return Char.IsDigit(Value); }
Char has a number of other static functions that check the character's
class.
FWIW, when I have a static method that is checking a 'constant' regex, I
normally create a static Regex field, then use that. This way the regex
object itself is not continueally recreated. I even consider making this
Regex compiled with the RegexOptions.Compiled option, to get even a little
more performance out of it. Seeing as its static, there is only going to be
one anyway.
Something like:
static readonly Regex thePattern = new Regex(@"^[0-9]+$",
RegexOptions.Compiled);
public static bool IsNumber( string value ) {
return thePattern.IsMatch(value); }
Hope this helps
Jay
"Tim Conner" <Ti*******@discussions.microsoft.com> wrote in message
news:08****************************@phx.gbl... Is there a way to write a faster function ?
public static bool IsNumber( char Value ) { if (Regex.IsMatch( Value.ToString(), @"^[0-9]+$" )) { return true; } else return false; }
I think, if I have to repat this some thousands time, it could become very time consuming.
Thanks in advance,
P.S. Is there in C# something similar to Delphi's sets ?
I have another similar routines, for check alpha numeric,
and to test for integers and floats. So, I did that just
by inertia <g>. I may change this routine since it is very
straight forward, numbers are numbers, so no more to check
here.
But for my other routines, I think I do need regex. For
example the following :
public static bool IsFloat( string Value)
{
if (Regex.IsMatch( Value.ToString(), @"^[+-]?([0-9]*\.?
[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$" ))
{
return true;
}
else return false;
}
I am using the static IsMatch of Regex. So I think I am
not recreating a regex object each time.
But your code seems slightly different.
But I am not sure about "that" difference <g>.
Would you mind to explain a bit more on this ?
Thanks in advance, -----Original Message----- Tim, In addition to Jon's comments.
Is there a reason you are not using the static
Char.IsDigit or Char.IsNumberfunction?
public static bool IsNumber( char Value ) { return Char.IsDigit(Value); }
Char has a number of other static functions that check
the character'sclass.
FWIW, when I have a static method that is checking
a 'constant' regex, Inormally create a static Regex field, then use that. This
way the regexobject itself is not continueally recreated. I even
consider making thisRegex compiled with the RegexOptions.Compiled option, to
get even a littlemore performance out of it. Seeing as its static, there
is only going to beone anyway.
Something like:
static readonly Regex thePattern = new Regex(@"^[0-9]
+$",RegexOptions.Compiled);
public static bool IsNumber( string value ) { return thePattern.IsMatch(value); }
Hope this helps Jay
"Tim Conner" <Ti*******@discussions.microsoft.com> wrote
in messagenews:08****************************@phx.gbl... Is there a way to write a faster function ?
public static bool IsNumber( char Value ) { if (Regex.IsMatch( Value.ToString(), @"^[0-9]
+$" )) { return true; } else return false; }
I think, if I have to repat this some thousands time, it could become very time consuming.
Thanks in advance,
P.S. Is there in C# something similar to Delphi's sets ?
.
Tim, I am using the static IsMatch of Regex. So I think I am not recreating a regex object each time.
Correct you are not explicitly creating a regex object each time, however
the static method IS implicitly creating a regex object each time for you.
Read the description of the static IsMatch carefully! http://msdn.microsoft.com/library/de...atchTopic3.asp
The Remarks state: "The two static IsMatch methods are equivalent to
constructing a Regex object with the specified regular expression pattern
and calling the instance method IsMatch. The static methods are provided to
allow an isolated, single use of a regular expression without explicitly
creating a Regex object."
Note "isolated, single use" and "equivalent to constructing a regex object"
in the above statement. I would expect your IsFloat method to be called a
number of different times from a number of different places...
But your code seems slightly different. But I am not sure about "that" difference <g>. Would you mind to explain a bit more on this ?
What do you mean different? Do you mean I simply return the bool value,
rather then checking for true and returning true?
you effectively have:
bool rc = Regex.IsMath(...)
if (rc)
return true
else
return false;
where as I effectively have:
bool rc = Regex.IsMath(...)
return rc;
I used an explaining variable in the above sample, however they are the
same.
Or that you were passing a char, I modified it to pass a string.
Or that I created an object, and use an instance method of the object?
In your IsFloat routine, I would simply use:
private static readonly Regex floatPattern = new
Regex(@"^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$",
RegexOptions.Compiled);
public static bool IsFloat(string value)
{
return floatPattern.IsMatch(value)
}
floatPattern is:
- private : as its an implementation detail
- static : as we only need one instance of it
- readonly : as we don't need to change it after its initialized
IsFloat uses the above Regex to check for a match, value is already a
string, so we do not need to call ToString a second time. Seeing as
Regex.IsMatch returns a bool, we can simply return this bool. IsFloat
encapsulates the Regex object.
Hope this helps
Jay
"Tim Conner" <Ti*******@discussions.microsoft.com> wrote in message
news:09****************************@phx.gbl... I have another similar routines, for check alpha numeric, and to test for integers and floats. So, I did that just by inertia <g>. I may change this routine since it is very straight forward, numbers are numbers, so no more to check here.
But for my other routines, I think I do need regex. For example the following :
public static bool IsFloat( string Value) { if (Regex.IsMatch( Value.ToString(), @"^[+-]?([0-9]*\.? [0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$" )) { return true; } else return false;
}
I am using the static IsMatch of Regex. So I think I am not recreating a regex object each time. But your code seems slightly different. But I am not sure about "that" difference <g>. Would you mind to explain a bit more on this ?
Thanks in advance,
-----Original Message----- Tim, In addition to Jon's comments.
Is there a reason you are not using the static Char.IsDigit or Char.IsNumberfunction?
public static bool IsNumber( char Value ) { return Char.IsDigit(Value); }
Char has a number of other static functions that check the character'sclass.
FWIW, when I have a static method that is checking a 'constant' regex, Inormally create a static Regex field, then use that. This way the regexobject itself is not continueally recreated. I even consider making thisRegex compiled with the RegexOptions.Compiled option, to get even a littlemore performance out of it. Seeing as its static, there is only going to beone anyway.
Something like:
static readonly Regex thePattern = new Regex(@"^[0-9] +$",RegexOptions.Compiled);
public static bool IsNumber( string value ) { return thePattern.IsMatch(value); }
Hope this helps Jay
"Tim Conner" <Ti*******@discussions.microsoft.com> wrote in messagenews:08****************************@phx.gbl... Is there a way to write a faster function ?
public static bool IsNumber( char Value ) { if (Regex.IsMatch( Value.ToString(), @"^[0-9] +$" )) { return true; } else return false; }
I think, if I have to repat this some thousands time, it could become very time consuming.
Thanks in advance,
P.S. Is there in C# something similar to Delphi's sets ?
.
> I have another similar routines, for check alpha numeric, and to test for integers and floats. So, I did that just by inertia <g>. I may change this routine since it is very straight forward, numbers are numbers, so no more to check here.
Don't validate to much.
Some day the marketing team will decide they can sell
this in Europe and you have to translate it.
And suddenly you validations go down the drain.
Your alpha numeric will not accept accented characters,
your float will not accept numbers where the
decimal point is comma, etc.
Mihai
Bsiang Tan <tb*********@hotmail.com> wrote: Why don't you try the framework given method ? Check the Char.IsNumber( ) ?
For example : Console.WriteLine(Char.IsNumber('8')); // Output: "True"
Actually, what was asked for is really Char.IsDigit (ie just 0-9) - but
I wouldn't have spotted that if you hadn't raised it :)
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
codymanix <do*********************@gmx.de> wrote: The simplest would be to do a float.Parse(myString) and check wheather a exception occures or not.
And the fastest would be to do some preliminary validation before
calling float.Parse. Again, writing a small routine which knows about
floating point formats is likely to be fairly simple, and significantly
faster than a regex.
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: actarus |
last post by:
I need a Regex that find just a text inside a string that has both text and
tags html,
for example :
string str = "<table ....><tr><td>my table</td></tr></table>
I want a Regex that return just...
|
by: Craig Kenisston |
last post by:
I have the sudden need to split a text that may have any of the
following tokens :
Words with quotes or double quotes.
Words with no quotes at all.
Numbers with and without decimal points, no...
|
by: Extremest |
last post by:
I have a huge regex setup going on. If I don't do each one by itself
instead of all in one it won't work for. Also would like to know if
there is a faster way tried to use string.replace with all...
|
by: Extremest |
last post by:
I am using this regex.
static Regex paranthesis = new Regex("(\\d*/\\d*)",
RegexOptions.IgnoreCase);
it should find everything between parenthesis that have some numbers
onyl then a forward...
|
by: Peter |
last post by:
Hi all,
I am searching through directories trying to find the prefix to a
number of files. Unfortunately the files don't have a standard naming
convention yet.
So some of them appear as:...
|
by: Mark Chambers |
last post by:
Hi there,
I'm seeking opinions on the use of regular expression searching. Is there
general consensus on whether it's now a best practice to rely on this rather
than rolling your own (string)...
|
by: Diwa |
last post by:
Hi Guys,
Is there any better way than below to find an int in a string (e.g.
"30" in "KFStat30A")
// --------------------------------------------------------------
#include <iostream>...
|
by: wildman |
last post by:
RE: Replacing Text without changing case??
This code works great, but case has to be exact.
Research.Text = Research.Text.Replace(textboxSearch.Text, "<b>" +
textboxSearch.Text + "</b>")
...
|
by: Vipul03 |
last post by:
I want to search a regex in perl without replacing it and without going line by line to search it
Any help will be apriciable
Thanks in advance
|
by: Faith0G |
last post by:
I am starting a new it consulting business and it's been a while since I setup a new website. Is wordpress still the best web based software for hosting a 5 page website? The webpages will be...
|
by: ryjfgjl |
last post by:
In our work, we often need to import Excel data into databases (such as MySQL, SQL Server, Oracle) for data analysis and processing. Usually, we use database tools like Navicat or the Excel import...
|
by: Charles Arthur |
last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
|
by: aa123db |
last post by:
Variable and constants
Use var or let for variables and const fror constants.
Var foo ='bar';
Let foo ='bar';const baz ='bar';
Functions
function $name$ ($parameters$) {
}
...
|
by: ryjfgjl |
last post by:
If we have dozens or hundreds of excel to import into the database, if we use the excel import function provided by database editors such as navicat, it will be extremely tedious and time-consuming...
|
by: emmanuelkatto |
last post by:
Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud.
Please let me know.
Thanks!
Emmanuel
|
by: BarryA |
last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
|
by: Sonnysonu |
last post by:
This is the data of csv file
1 2 3
1 2 3
1 2 3
1 2 3
2 3
2 3
3
the lengths should be different i have to store the data by column-wise with in the specific length.
suppose the i have to...
|
by: Hystou |
last post by:
There are some requirements for setting up RAID:
1. The motherboard and BIOS support RAID configuration.
2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
| |