Re: Convert or Parse - C# Discussion Boards

Goersch123412-Feb-09 8:29

12-Feb-09 8:29

I tried "RSS 2.0 Framework" but it gets into the same trouble. That's why
I tried to run something more simple - with the same result.

Convert or Parse

Lodeclaw12-Feb-09 6:43

Lodeclaw

12-Feb-09 6:43

I was told that the most common method to convert a value is to use the Parse method, however it only works with strings, as you all know...

So I was wondering, then: if you're converting a non-string value to another non-string, is it better/more efficient to use for example...

Convert.ToInt32(value);
or
int.Parse(value.ToString());

Thanks guys!

Re: Convert or Parse

Luc Pattyn12-Feb-09 6:56

Luc Pattyn

12-Feb-09 6:56

Hi,

it depends on the Type of your value:

if value is a string, then value.ToString() is redundant, and both Convert and int.Parse would behave identically (in fact one is calling the other).

if value is some kind of integer to begin with, Convert.ToInt32() is much faster, since no conversion from integer to string, and no conversion from string to int are involved.

if value is something else (a DateTime, a user-defined type, ...) Convert will not accept it,
whereas the value.ToString() result may or may not look like an integer, and be acceptable to int.Parse

Smile | :)

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modified on Sunday, June 12, 2011 8:02 AM

Re: Convert or Parse

akidan12-Feb-09 7:14

akidan

12-Feb-09 7:14

Luc summed it up well, but I just wanted to add one other non-obvious difference.

With value = null;
Convert.ToInt32(value) returns 0
int.Parse(value.ToString()) throws NullReferenceException.
int.Parse(value) throws ArgumentNullException. (if value is String)

Re: Convert or Parse

freakyit12-Feb-09 9:18

freakyit

12-Feb-09 9:18

hi,

look at the int.TryParse(object,out bool) functionality.
The boolean value stands up for true (parseable) and false(not parseable) about trying to parse the value. There will be no exception raised. if you want to use int.Parse instead of TryParse you need to catch the exception with try catch..

bless Smile | :)

Re: Convert or Parse

PIEBALDconsult12-Feb-09 12:02

PIEBALDconsult

12-Feb-09 12:02

In my opinion the only worthwhile member of Convert is System.Convert.ChangeType, will that do what you want?

Otherwise, maybe a simple cast is what you want?

Or, if it's a type of your own creation, perhaps an implicit conversion operator?

You would have to give us more information.

Re: Convert or Parse

Mycroft Holmes12-Feb-09 14:15

Mycroft Holmes

12-Feb-09 14:15

Hijack

If you have 2 classes that are identical (set of credentials) can you use System.Convert.ChangeType to convert one to the other?

Never underestimate the power of human stupidity
RAH

Re: Convert or Parse

Guffa12-Feb-09 15:06

Guffa

12-Feb-09 15:06

The most common method to convert a non-string value to an int is implicit or explicit casting. Example:

// implicit casting:
byte b = 42;
int answer = b;

// explicit casting:
double d = 42.0;
int answer = (int)d;

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

ASP file not being able to to find a class that is in the same namespace.

Steve Holdorf12-Feb-09 6:40

Steve Holdorf

12-Feb-09 6:40

I have an ASP file and a Customer class both in the same namespace. When I compile I receive the error: The type or namespace name 'Customer' could not be found (are you missing a using directive or an assembly reference?). I have checked and the asp page

Inherits="PopupApplication.InitDialog"

And the Customer was created in that namespace and has that namespace in the class file. Can anyone help?

Thanks,

Steve

Re: ASP file not being able to to find a class that is in the same namespace.

Calin Tatar12-Feb-09 11:59

Calin Tatar

12-Feb-09 11:59

Make sure your class is decorated with "public".
Also, you may try to move it in App_Code folder.

Calin

pivot table

Dushan12312-Feb-09 6:10

Dushan123

12-Feb-09 6:10

is there is any free pivot chart Controller for visual studio

Dushan Perera

Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

Tarini Singh12-Feb-09 5:54

Tarini Singh

12-Feb-09 5:54

Hi Team,

Required functional is to access the Base class Method itself on other hierarchy class but need to restrict the base class method on derive class.

For Example,

Base Class B --------> Having Static Method M

Derive D from B 
 Need to restrict the access of Method M through D but should be accessible  through B.

Can anybody help me out.

Thanks in Advance
Tarun Singh

Re: Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

musefan12-Feb-09 6:00

musefan

12-Feb-09 6:00

maybe use the sealed keyword, im not sure thou

no, dont think so lol... try 'explicit' keyword instead

If only MySelf.Visible was more than just a getter...

A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting

Re: Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

DaveyM6912-Feb-09 6:19

DaveyM69

12-Feb-09 6:19

explicit is for overloading conversion operators.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Re: Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

Tarini Singh12-Feb-09 23:26

Tarini Singh

12-Feb-09 23:26

No, Not Fulfill the functionality.

Re: Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

DaveyM6912-Feb-09 6:18

DaveyM69

12-Feb-09 6:18

Not sure you can.

The best I can think of is to mark D's M as internal new, that way it won't be visible outside that particular assembly but B's M will.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Re: Need to restric Base Method on Derive and Access on Other Namespace hierarchy class.

ABitSmart12-Feb-09 15:34

ABitSmart

12-Feb-09 15:34

One way I can see doing this is by adding a level of hierarchy,

Base Class B //Not having Method M, but all others

Derived Class B_With_M //Deriving from B but and having Method M (as protected to restrict it to only derived class)

Derived Class D //Deriving from B, this will be your class with Base as B(through hierarchy) and not having M.

All other classes whom you want to give access to M will derive from B_With_M and not from B.

problem with é, à, è

abbd12-Feb-09 5:39

abbd

12-Feb-09 5:39

Hello,
when reading a text file, the letters having accents, they appear square caps in a message box, how can we keep the same letters? thank you verry much.

Re: problem with é, à, è

musefan12-Feb-09 5:46

musefan

12-Feb-09 5:46

its down to the encoding of the text, as far as i know you cant change that with the message box directly but maybe it can be set in the system

If only MySelf.Visible was more than just a getter...

A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting

Re: problem with é, à, è [modified]

Luc Pattyn12-Feb-09 5:47

Luc Pattyn

12-Feb-09 5:47

Hi,

Most probably the MessageBox is not at fault, the way you read your file is.

each text file uses some way to identify characters that are outside the regular ASCII character set
(which is less than 128 chars). You either use a "code page" telling what the byte values [128,255]
represent, or some more elaborate scheme such as UTF8 or Unicode, to get access to a much larger
character set where some or all characters use 2 bytes.

UTF8 and Unicode files start with a special byte sequence to identify them. When no byte sequence
is present, your best guess may be to use the code page that suits your locale; I typically use
new Encoding(1252) yielding a West-European code page.

So when reading a text file, you should apply the right "encoding" and pass that to your
input methods, e.g. File.ReadAllText Method (String, Encoding)

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Sunday, June 12, 2011 8:00 AM

Can we know the extention of code base 64 digits??

abbd12-Feb-09 5:21

abbd

12-Feb-09 5:21

Hello,

i encode the word file using this code :

Convert.ToBase64String(data),

but when i decode the code 64digits, we mus add an extention like .doc, can we know the extention of code base 64 digits? thank you verry mutch.

Re: Can we know the extention of code base 64 digits??

musefan12-Feb-09 5:25

musefan

12-Feb-09 5:25

if it is a data file i think you would need to check the file header information and determine the filetype from that then choose you extension, this however would mean you need to have a list of file associations for different filetypes. You best option might be to store the extension somewhere before conversion if that is posible?

If only MySelf.Visible was more than just a getter...

A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting

Re: Can we know the extention of code base 64 digits??

Rob Philpott12-Feb-09 5:33

Rob Philpott

12-Feb-09 5:33

If I understand correctly, then no you can't. Encoding a word file (or any file) for that matter to base64 just stores the raw data of the file, not the name or extension or file data.

Regards,
Rob Philpott.

Re: Can we know the extention of code base 64 digits??

abbd12-Feb-09 5:36

abbd

12-Feb-09 5:36

so we can't get the extension of the original file?? i don't like save the extension elonely in another filed, thank you verry mutch

Re: Can we know the extention of code base 64 digits?? [modified]

Luc Pattyn12-Feb-09 5:42

Luc Pattyn

12-Feb-09 5:42

Hi,

if you are creating an app that does Base64 file conversion, you have several options:
1. you could generate a file that has the original filename and append "64" to the extension;
2. you could generate a file that holds at least two strings, the first being the filename+extension,
the next one being the base64-encoded data.

BTW: I hope you are not reading all the data first, then turning that into a single (possibly huge) string. If you were to do so, a large word document (one that Word your barely manages to open on
your system) would not fit in your conversion app since that would have to hold both the original
and the converted data (which is 33% larger in size). The right way is to have a loop reading
say 64KB of data and outputting that in base64, then repeat until all is done.

[ADDED]
if you are storing binary file data in a database, I suggest you use two fields, one for the
filename, one for the data.
[/ADDED]

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

modified on Thursday, February 12, 2009 11:49 AM

modified on Sunday, June 12, 2011 8:01 AM

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