Re: Trouble Using System.Array.ForEach

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The reason that the Array.ForEach Generic method is not suitable for your purposes in this case is that on each iteration of the 'hidden' loop, each element of the array is paseed to the Action delegate Sub, ByVal. Note that the Action delegate is a Sub and not a Function. This is complicated in that the elements you are dealing with are strings, which, although being a reference type, are immutable. Therefore the string that is passed to the delegate is returned unaltered and the parent array is not modified.

Even if you use a For Each loop on the array of strings, the same behaviour is exhibited because each iteration of the loop is operating on a copy of the array element and not the array element itself, e.g.:

Dim _ss As String() = DateTimeFormatInfo.CurrentInfo.DayNames

For Each _s As String in _ss
_s = "'" & _s & "'"
Next

does not work because _s is only a copy of an element of _ss, whereas:

Dim _ss As String() = DateTimeFormatInfo.CurrentInfo.DayNames

For _i as Integer = 0 to _ss.Length - 1
_ss(_i) = "'" & _ss(_i) & "'"
Next

works because the content of each element is being manipulated directly via the index.

While the Framework includes many methods on various classes that provides, with a single call, the functionality that we might once have had to write some code to achieve, there will not necessarily be a suitable Framework method for everything you want to do.

NEVER be scared to get your hands dirty and write a bit of code and NEVER expect that someone is going to provide a particular 'method' ready for you to use 'out of the box'.

As a further word of advice, programming is not a competition to use the least amout of code possible. It is rare that the smallest amount of code is the most efficient.


"Nathan Sokalski" <njsokalski@xxxxxxxxxxx> wrote in message news:OYpdeok7HHA.4476@xxxxxxxxxxxxxxxxxxxxxxx
You are definitely correct that you proved me wrong about the loop thing, at least for the scenario of simply adding quotes, thank you very much for providing that solution. However, I still have the scenarios where I need to use only the first letter, or the first two letters, or capitalize, etc., and your solution does not work for these (unless I'm missing something again), which I think are the scenarios I was thinking about when I mentioned the If Then statement. And you may be right about the ForEach not fitting my conditions, I really can't say for sure since I have never had the opportunity to use ForEach, but either way, it never hurts to have extra knowledge so that if a situation were to come up where it was fit I would know it. Thanks.
--
Nathan Sokalski
njsokalski@xxxxxxxxxxx
http://www.nathansokalski.com/

"ModelBuilder" <ModelBuilder@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message news:EA14ADC5-F596-47DB-AE63-793851793A56@xxxxxxxxxxxxxxxx
It appeared from your last question, that you thought using a loop to build
the comma separated list would require an if-then clause to remove the comma
before the first iteration. The code I provided eliminates this.

You have shown several cases where you seem to want a solution "of a
particular form", rather than a solution. Perhaps someone can post an
example where Array.ForEach solved a problem for them, but to be honest with
you, I have never run into a case where it helped. I think if someone has an
example, it won't exactly fit your conditions.

"Nathan Sokalski" wrote:

I know how to do string manipulation, that is a very simple task. However,
in several of my cases I want to not only add quotes to each element, but
take the substring of it as well (for example, in some cases I want an array
of only the first letter of each day). The techniques people have mentioned
so far are great when I want the entire name, but when I need to do
something like get just the first letter, or if I want it in all capitals,
etc., I would require either a loop of some sort (which is what I am trying
to avoid) or the ForEach method. I appreciate everyone's suggestions on how
to use loops and string manipulation, but unfortunately (well, fortunately
actually) I already know those techniques. So unless you are going to help
me figure out how to use ForEach, save yourself the effort of showing me
string manipulation and help someone else that is still learning loops and
all the string manipulation techniques. But I still thank you for your time
and effort.
--
Nathan Sokalski
njsokalski@xxxxxxxxxxx
http://www.nathansokalski.com/

"ModelBuilder" <ModelBuilder@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:19073C71-3202-4285-BBEB-59A81BDCF386@xxxxxxxxxxxxxxxx
> This will avoid the leading comma:
>
>
> dim n as integer = CurrentInfo.DayNames.Length - 1
> dim s as string = CurrentInfo.DayNames(0)
>
> for i = 1 to n
> s = string.Format("{0}, {1}", s, CurrentInfo.DayNames(i))
> next
>
>
> "Nathan Sokalski" wrote:
>
>> That would get me the quotes around each of the days, but I was >> hoping to
>> do
>> something like this:
>>
>> String.Join(",",System.Globalization.DateTimeFormatInfo.CurrentInfo.DayNames())
>>
>> so that I could have the DayNames separated by commas. However, the >> code
>> that I have above would not place each day inside quotes. Do I know >> of
>> ways
>> to create this comma-delimited String? Of course, but using a for >> loop
>> would
>> require me to either include an if statement determining when I am at >> the
>> last value or manually remove the comma from the end of the String. I
>> figured if I could just use the String.Join instead, I wouldn't have >> to
>> deal
>> with so many Strings and If statements. And, even though it may be >> just a
>> thirst for knowledge, I would like to know how to use the ForEach >> method
>> for
>> future reference. Thanks.
>> -- >> Nathan Sokalski
>> njsokalski@xxxxxxxxxxx
>> http://www.nathansokalski.com/
>>
>> "ModelBuilder" <ModelBuilder@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in >> message
>> news:5E4EACCE-CF4D-4FA6-B2BB-51B8082841C8@xxxxxxxxxxxxxxxx
>> > The Action type for the ForEach method requires a subroutine that >> > takes
>> > no
>> > parameters. I've never tried this method, but it doesn't seem >> > useful
>> > for
>> > your situation. How about starting with the following:
>> >
>> >
>> > For Each dayofweek As String In _
>> >
>> > System.Globalization.DateTimeFormatInfo.CurrentInfo.DayNames
>> >
>> > Console.Out.WriteLine(AddQuotes(dayofweek))
>> > Next
>> >
>> >
>> > "Nathan Sokalski" wrote:
>> >
>> >> I am trying to use the System.Array.ForEach method in VB.NET. The
>> >> action
>> >> that I want to perform on each of the Array values is:
>> >>
>> >> Private Function AddQuotes(ByVal value As String) As String
>> >> Return String.Format("'{0}'", value)
>> >> End Function
>> >>
>> >> Basically, I just want to surround each value with single quotes.
>> >> However, I
>> >> am having trouble getting this to work using the >> >> System.Array.ForEach
>> >> method. This may be partially because I am not very experienced >> >> with
>> >> Actions
>> >> or Delegates, so if somebody could tell me what I am doing wrong, >> >> I
>> >> would
>> >> appreciate it. Thanks. (NOTE: The Array that I want to modify the
>> >> values
>> >> of
>> >> is not one that I have permission to modify (it is
>> >> System.Globalization.DateTimeFormatInfo.CurrentInfo.DayNames()), >> >> so if
>> >> anybody knows of a way to do this inline without declaring another
>> >> Array,
>> >> that would be nice as well)
>> >> -- >> >> Nathan Sokalski
>> >> njsokalski@xxxxxxxxxxx
>> >> http://www.nathansokalski.com/
>> >>
>> >>
>> >>
>>
>>
>>






.

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