Re: C# Multi-line String Literals
- From: Kerneels Roos <kerneels@xxxxxxxxx>
- To: programmingblind@xxxxxxxxxxxxx
- Date: Wed, 11 Aug 2010 11:03:52 +0200
Thanks for all the info Rick. I don't mind long emails if they are
interesting and convey good info ha ha!
Oh yeah, I totally agree with you about actual values which one will do via
parameterised queries. What I meant with multi line strings is simply that,
for a big query you don't want to put it all on one line -- it becomes very
hard to read it like that. Splitting it across lines is a much better
approach. Previously I thought that the "+" string concatenation operator
was very slow, but now it looks like it's not really a problem if the string
is a constant, meaning, the value is totally known at compile time.
Some guy inspected the actual byte code and saw that the compiler is smart
enough to make one long string if it's just a constant string value, even if
you use "+" operators. The "@" operator for denoting very literal string is
definately also treated like that by the compiler with the exception that
you introduce a glut of white space and new line chars since the compiler
can surely not remove those, that would attack the integrity of your code
itself or data rather.
StringBuilder is for sure by far the best way to go if you are going to
append to a string in a loop or something -- append a variable number of
times, but my question is just what about if you are appending a fixed
number of times, like when you want to display some sql string literal more
reader friendly, is the StringBuilder approach still more eficient? It cant'
b.
Regards
On Wed, Aug 11, 2010 at 10:43 AM, RicksPlace <ofbgmail@xxxxxxxxx> wrote:
> Hi: OK, first a StringBuilder creates one variable to hold the string. No
> matter how many times you change that string you will have one variable and
> that will save space and perform faster than using a standard string
> variable if you change the value of the StringBuilder object more than a few
> hundred times or so. A standard String variable is created new each time you
> change the contents of the string so you can get a bunch of variables
> created if you change the value held in the string. Now, it looks like you
> are trying to build a Database Query String in a StringBuilder or String
> Variable. In your example you include the where clause and the value to test
> for "5" if I remember in the string itself. This is not how you would
> creat4e a Query String if you are going to have diferent values for a where
> clause or other clauses that might have values that would change. You can
> build a query string and use it by passing the string and a value to the DB
> Engine but the correct method would be to use a Parameterized query. In your
> example the query might execute ok but what if you wanted to use a text
> value in the where clause? Then you would have to use single quotes or,
> depending on the DB Engine settings use Single quotes for the query string
> and double quotes for the value. You want to use a Parameterized query if
> you are learning to work with a Sql Server or Sql CE Database, likely an
> Access DB or other DB if Parameterized querys are supported for non MS
> Databases as well.
> So, you can use either StringBuilder or a standard string to build a
> string. By the way, I am not sure about Multi-Line strings, a string is one
> long line of text as far as I know. You can include line breaks in a string
> but the string itself is one long line of text. If you want multi-lines you
> would use a list object or a table or array object to hold each line of
> text. A list might look like:
> List.( Of String). Then you can use the list of strings by using the
> methods and properties of the List Object like the Append, For Each, Remove
> and all that jazz. But, it sounds like you just want to build either a
> standard query string or want to use Parameterized queries for the code you
> are working on. PS, my list object code is from vb.net but I believe it is
> a Framework object so should be the same in C# or other VS Languages. Well,
> sorry this is sort of long but a simple answer is that there is actually no
> such thing as a multi-line string. You can code several lines to build a
> string and variious objects that hold strings like an array or list but each
> string is one long group of characters so I don't understand the question
> exactly.
> In the MS Docs the StringBuilder AppendLine just addes a line break in the
> long string you are building:
> According to the MS Docs:
> StringBuilder.AppendLine Method
> Appends the default line terminator to the end of the current
> StringBuilder
> Well, my answer is to use the simple string object unless you will be
> changing the string variable more than say 50 or 100 times without
> destroying it by leaving the class or method where it is defined so you
> don't build thousands of variables, one each time you change the value of
> the string.
> Rick USA
> ----- Original Message -----
>
> *From:* Kerneels Roos <kerneels@xxxxxxxxx>
> *To:* programmingblind <programmingblind@xxxxxxxxxxxxx>
> *Sent:* Wednesday, August 11, 2010 3:57 AM
> *Subject:* C# Multi-line String Literals
>
> Hi List,
>
> Three ways to do this, which one is best:
>
> 1.
> StringBuilder sb = new StringBuilder();
> sb.AppendLine("SELECT id ");
> sb.AppendLine("FROM my_table ");
> sb.AppendLine("WHERE id > 5");
>
> 2.
> string myMultiLine = "SELECT id "
> + "FROM my_table"
> + "WHERE id >5";
>
> 3.
> string myMultiLine = @"SELECT id
> FROM my_table
> WHERE id > 5";
>
> Method 1 is the usual way, 2 introduces extra whitespace and lime breaks,
> and 3 apparently does not result in slower code if the whole string is known
> at compile time -- the compiler is smart enough to make it into one string
> (see: http://jameskovacs.com/2007/02/12/multiline-strings-in-c/ ).
>
> If you know that you are going to have to tweak the string and have a few
> round trips to the query analyzer I would say that 2 would actually be best
> since you only have to remove the first @" and last "; and the literal
> string will run. Once you know the string is perfect I would say method 3 is
> the best since it looks like it might be faster than method 1 and does not
> have the extra, maybe unwanted additional whitespace and new line chars that
> method 2 introduces.
>
> What do you guys think?
>
> Regards,
>
> --
> Kerneels Roos
> Cell/SMS: +27 (0)82 309 1998
> Skype: cornelis.roos
>
> The early bird may get the worm, but the second mouse gets the cheese!
>
>
>
--
Kerneels Roos
Cell/SMS: +27 (0)82 309 1998
Skype: cornelis.roos
The early bird may get the worm, but the second mouse gets the cheese!
Other related posts:
