C# Discussion Boards - CodeProject

13-Jan-09 0:04

how to implement escape sequence like ( ) / \

these in coding

Regex.Matches(str1, " [\,/]");

this shows escape sequence error

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SeMartens13-Jan-09 0:10

13-Jan-09 0:10

Hi,

you only have to escape the \ by using \\. So your regex will look like this:

<br />
Regex.Matches(str1, "[\\,/]");<br />

Regards
Sebastian

It's not a bug, it's a feature!

Me in Softwareland.

lawrenceinba13-Jan-09 0:15

13-Jan-09 0:15

s = Regex.Replace(s," ( ", " ");
s = Regex.Replace(s," ) ", ",");

how about here... same problem

thanks

the quieter u become more u hear

SeMartens13-Jan-09 0:17

13-Jan-09 0:17

Hmm, that should be no problem. Pasted it in my code and the IDE doesn't show an error. Do you get a runtime error or a compiler error? Could you please provide the whole error text?

Thanks.

It's not a bug, it's a feature!

Me in Softwareland.

lawrenceinba13-Jan-09 0:20

13-Jan-09 0:20

parsing " ( " - Not enough )'s.

this is the error msg shown.... runtime error

compling suceeded.....

the quieter u become more u hear

SeMartens13-Jan-09 0:26

13-Jan-09 0:26

That is because round paranthesis are a special character within regex. You have to escape them also like this:

<br />
s = Regex.Replace(s," \( ", " ");<br />

It's not a bug, it's a feature!

Me in Softwareland.

lawrenceinba13-Jan-09 0:51

13-Jan-09 0:51

thanks a lot......

but single slash \ shown error again......

used \\ and executed sucessfully

thank uuuuu

the quieter u become more u hear

Guffa13-Jan-09 0:53

Guffa

13-Jan-09 0:53

Actually you have to escape the parenthesis in the regular expression, not the string. Put a backslash in the pattern:

s = Regex.Replace(s," \\( ", " ");

Despite everything, the person most likely to be fooling you next is yourself.

S. Senthil Kumar13-Jan-09 0:56

S. Senthil Kumar

13-Jan-09 0:56

Or you could use the verbatim operator

s = Regex.Replace(s, @"\(", " ");

Saves one escaping.

Regards
Senthil [MVP - Visual C#]
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Threads and random()

gudrunkr13-Jan-09 0:01

gudrunkr

13-Jan-09 0:01

Hi,
I'm making a thread that generates random numbers into an array. Then I make 2 threads from that one I made, but I get the same random numbers in each thread. I've tried to use lock or Monitor, what am I doing wrong?

the C# girl

SeMartens13-Jan-09 0:06

13-Jan-09 0:06

Hi,

could you please provide the code you are using to create the random numbers? Maybe you are using the same seed for the creation of the numbers, but that's something that can be seen in the code.

Regards
Sebastian

It's not a bug, it's a feature!

Me in Softwareland.

gudrunkr13-Jan-09 0:13

gudrunkr

13-Jan-09 0:13

Hi,
I've just got!!!
I put static in front of the "Random random = new Random();" not private/public and know it works. Thanks.

SeMartens13-Jan-09 0:15

13-Jan-09 0:15

Well, you're welcome... Smile | :)

It's not a bug, it's a feature!

Me in Softwareland.

Question on SqlDataReader[string name]

S. Senthil Kumar13-Jan-09 1:04

S. Senthil Kumar

13-Jan-09 1:04

Do you know why it didn't work first?

The Random class uses the current time as the "seed" for generating random numbers. Because you created two instances, one for each thread, and the two threads started running in parallel right away, both of them got the same seed and therefore generated the same sequence of random numbers.

BTW, the MSDN doc says that instance methods on the Random class are not thread safe - you might have to look out for that.

Regards
Senthil [MVP - Visual C#]
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Dewald12-Jan-09 23:08

Dewald

12-Jan-09 23:08

Hi all,

If I have a SqlCommand of which the query includes a join, let's say something as follows:

SELECT * FROM Stock INNER JOIN Transactions ON Stock.StockID = Transactions.StockID

how can I use SqlDataReader[string name] to obtain values from the result coming from a specified field in a specified table? In other words, if both the tables Stock and Transactions include a field with the name Price, the result in SqlDataReader will include two columns, both named Price. If I want to compare the two for instance, how can I force SqlDataReader[string name] to return Stock.Price or Transactions.Price?

I was hoping for something like:

using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader())
{
    while (sqlDataReader.Read())
    {
        if (sqlDataReader["Stock.Price"] != sqlDataReader["Transactions.Price"])
            ShowError("Item was sold at incorrect price");
    }
}

This is a simple example but I hope you get the point. I'm hoping that it isn't necessary to change my SQL query so as to give explicit names to the different columns.

SeMartens12-Jan-09 23:14

12-Jan-09 23:14

Hi Dewald,

i'm surprised that the query can be executed with two tables containing a column with the same name. AFAIK you have to rewrite your query to give the two columns explicit names. If I understood the concept of datareaders right, the reader doesn't know that the query contains two tables. For him it is only one table (more like a view).

If there is another solution than rewriting the query, i would be very interested to hear about.

Regards
Sebastian

It's not a bug, it's a feature!

Me in Softwareland.

Wendelius12-Jan-09 23:35

Wendelius

12-Jan-09 23:35

Dewald wrote:
other words, if both the tables Stock and Transactions include a field with the name Price, the result in SqlDataReader will include two columns, both named Price

AFAIK, that wouldn't be possible. Since the Item is an indexer to the column list, there cannot be multiple instances with exactly the same name (which one would the indexer return or how would you refer to the other one, price or price Smile | :)

).

I think the reader works as other classes in the SqlClient so it will add an ordinal number to the end of the column if several columns exists with the same name. So I guess your other column is Price1. The downside is that you cannot be sure which one it is.

Dewald wrote:
sqlDataReader["Stock.Price"]

Single Item is not structural so the dot notation in this case wouldn't have any meaning if structure is considered (although the name of a column can contain a dot).

So after all, the most reliable way is to rewrite the sql. One idea could be that you include your logic (Stock.Price != Transactions.Price) to the sql statement itself using CASE and perhaps event use the condition in where logic (depending what you want). This way your program would have more prepared results and it would be easier to investigate them and perhaps the amount of rows returned would be smaller. But all of this depends on your requirements and logic.

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Dewald12-Jan-09 23:55

Dewald

12-Jan-09 23:55

Mika Wendelius wrote:
AFAIK, that wouldn't be possible. Since the Item is an indexer to the column list, there cannot be multiple instances with exactly the same name (which one would the indexer return or how would you refer to the other one, price or price ).

OK thanks, at least I can stop trying to make it work now. Guess I'll just have to rewrite the SQL to give the columns explicit names.

However...

Mika Wendelius wrote:
One idea could be that you include your logic (Stock.Price != Transactions.Price) to the sql statement itself using CASE and perhaps event use the condition in where logic (depending what you want).

Of course! Excellent suggestion. In this instance it is actually exactly what I need and should have done from the start. For future problems where this wouldn't suffice I will just rewrite the SQL though.

Thanks for the help.