Converting Regular expression match

[Paul Johnston]

Hi Just started using c# to do a task I usually use Perl to do and hit
a limit in my knowledge :-)
I have a program which reads from a large text file, extracts certain
lines then gets a string from these lines.

Question
If the object I extract is in the form of a number how can I cast it
into a number so I can prerform mathematical operations on it ?


The following code:

foreach (Match theMatch in theMatches1)
{
if (theMatch.Lengt h !=0)
{
Console.WriteLi ne("The match is
{0}",theMatch.T oString());
Console.WriteLi ne(theMatch.Gro ups["prob"]);
Console.WriteLi ne("Picking out the number {0} ",
theMatch.Groups["prob"]);
}
}

Gives me the following output:

The match is -0.9454 <s> The 0.1170
-0.9454
Picking out the number -0.9454

How can I turn theMatch.Groups["prob"] into say a double

TIA Paul

[Wessel Troost]

Re: Converting Regular expression match

> How can I turn theMatch.Groups["prob"] into say a double[color=blue]
>[/color]
Here's just two of the many ways:

double dProb = Convert.ToDoubl e( theMatch.Groups["prob"] );

or:

double dProb = double.Parse( theMatch.Groups["prob"] );

Greetings,
Wessel

[Paul Johnston]

Re: Converting Regular expression match

On Fri, 29 Jul 2005 10:31:45 +0200, "Wessel Troost"
<nothing@like.t he.sun> wrote:
[color=blue][color=green]
>> How can I turn theMatch.Groups["prob"] into say a double
>>[/color]
>Here's just two of the many ways:
>
> double dProb = Convert.ToDoubl e( theMatch.Groups["prob"] );
>
>or:
>
> double dProb = double.Parse( theMatch.Groups["prob"] );
>
>Greetings,
>Wessel[/color]


The first compiles but gives a run time error:

Unhandled Exception: System.InvalidC astException: Specified cast is
not valid.
at System.Convert. ToDouble(Object value)
at Wordgrams.Main( String[] args)


The second will not compile and gives:

wordgrams4.cs(6 0,35): error CS1502: The best overloaded method match
for
'double.Parse(s tring)' has some invalid arguments
wordgrams4.cs(6 0,49): error CS1503: Argument '1': cannot convert from
'System.Text.Re gularExpression s.Group' to 'string'

Coming to a strongly typed language is such a different world :-)

[Hans Kesting]

Re: Converting Regular expression match

Paul Johnston wrote:[color=blue]
> On Fri, 29 Jul 2005 10:31:45 +0200, "Wessel Troost"
> <nothing@like.t he.sun> wrote:
>[color=green][color=darkred]
>>> How can I turn theMatch.Groups["prob"] into say a double
>>>[/color]
>> Here's just two of the many ways:
>>
>> double dProb = Convert.ToDoubl e( theMatch.Groups["prob"] );
>>
>> or:
>>
>> double dProb = double.Parse( theMatch.Groups["prob"] );
>>
>> Greetings,
>> Wessel[/color]
>
>
> The first compiles but gives a run time error:
>
> Unhandled Exception: System.InvalidC astException: Specified cast is
> not valid.
> at System.Convert. ToDouble(Object value)
> at Wordgrams.Main( String[] args)
>
>
> The second will not compile and gives:
>
> wordgrams4.cs(6 0,35): error CS1502: The best overloaded method match
> for
> 'double.Parse(s tring)' has some invalid arguments
> wordgrams4.cs(6 0,49): error CS1503: Argument '1': cannot convert from
> 'System.Text.Re gularExpression s.Group' to 'string'
>
> Coming to a strongly typed language is such a different world :-)[/color]

theMatch.Groups["prob"] is a "Group". Convert.ToDoubl e and double.Parse
don't know how to convert that into a double (as you found out). They *do*
know how to convert from string though.

So the solution is easy: add a .Value to get the matched substring:
theMatch.Groups["prob"].Value

Hans Kesting

[Wessel Troost]

Re: Converting Regular expression match

> The first compiles but gives a run time error:[color=blue]
>[/color]
Sorry, I was assuming theMatch.Groups["prob"] returned a string.

Replace

theMatch.Groups["prob"]

with

theMatch.Groups["prob"].Value

That should work.

Greetings,
Wessel

[Paul Johnston]

Re: Converting Regular expression match

On Fri, 29 Jul 2005 11:15:18 +0200, "Wessel Troost"
<nothing@like.t he.sun> wrote:
[color=blue][color=green]
>> The first compiles but gives a run time error:
>>[/color]
>Sorry, I was assuming theMatch.Groups["prob"] returned a string.
>
>Replace
>
> theMatch.Groups["prob"]
>
>with
>
> theMatch.Groups["prob"].Value
>
>That should work.
>
>Greetings,
>Wessel[/color]


Converted the group to a string then the string to a double and it
works !
Fun this :-)

Thanks for all the help Paul