How to deal with non alpha numeric characters asp.net vb? - vb.net

I am processing a lot of CSV files that have people data and occasionally names are used non-alpha numeric characters like á and those all become � symbols in the datatable. How do i prevent this problem ? I just wanna leave all the names as they are in the file without making any changes.
Thanks,
L

The most common reason for this is that it is actually encoded in ISO-8859-1 and interpreted as UTF-8. For less common reasons, the same principle applies, that is, something is in different encoding that it claims to be.

Change the character encoding in the database or decode it when you read from the DB.

While processing, you need a Reader or something. I suggest you configure it by using a System.Encoding.UnicodeEncoding or UTF32Encoding.

Related

How to find Bad characters in the column

I am trying to pull 'COURSE_TITLE' column value from 'PS_TRAINING' table in PeopleSoft and writing into UTF-8 text file to get loaded into Workday system. The file is erroring out while loading because of bad characters(Ã â and many more) present in the column. I have used a procedure which will convert non-ascii value into space. But because of this procedure, the 'Course_Title' which are written in non-english language like Chinese, Korean, Spanish also replacing with spaces.
I even tried using regular expressions (``regexp_like(course_title, 'Ã) only to find bad characters but since the table has hundreds of thousands of rows, it would be difficult to find all bad characters. Please suggest a way to solve this.
If you change your approach, this may work.
Define what you want, and retrieve it.
select *
from PS_TRAINING
where not regexp_like(course_title, '[0-9A-Za-z]')```
If you take out too much data, just add it to the regex

Where can I a mapping of Identity-H encoded characters to ASCII or Unicode characters?

I have a PDF generated by a third party. I am trying to get the text out of it, but neither pdf2text nor copying and pasting results in readable text. After a little digging in the output (of either of two) I found that each character on the screen is made up of three bytes. For example, "A" is the bytes ef, 81, and 81. Looking at the metadata on the PDF it claims to be encoded in Identity-H, so I assume what I am seeing is a set of characters encoded in Identity-H. I have a partial mapping based on the documents I already have, but I want to make a more complete mapping. To do that I need something like an ASCII table for Identity-H.
It is not always possible to extract text from a PDF especially when the /ToUnicode map is missing as pointed out by mkl.
If it is not possible to cut and paste the correct text from Acrobat then you will have very little chance of extracting the text yourself. If Acrobat cannot extract it then it is very unlikely that any other tool can extract the text correctly.
If you manually create an encoding table then you could use this to remap the extracted characters to their correct values but this most likely will only work for this one document.
Often this is done on purpose. I have seen documents that randomly remap characters differently for each font in the dot. It is used as a form of obfuscation and the only real way to extract text from these PDF's is to resort to OCR. There are many financial reports that use this type of trick to stop people from extracting their data.
Also, Identity-H is just a 1:1 character mapping for all characters from 0x0000 to 0xFFFF. ie. Identity is an identity mapping.
Your real problem is the missing /ToUnicode entry in this PDF. I suspect there is also an embedded CMap in your PDF that explains why there could be 3 bytes per character.

Weird character (�) in SQL Server View definition

I have generated the Create statement for a SQL Server view.
Pretty standard, although there is a some replacing happening on a varchar column, such as:
select Replace(txt, '�', '-')
What the heck is '�'?
When I run that against a row that contains that character, I am seeing the literal '?' being replaced.
Any ideas? Do I need some special encoding in my editor?
Edit
If it helps the end point is a Google feed.
You need to read the script in the same encoding as that in which it was written. Even then, if your editor's font doesn't include a glyph for the character, it may still not display correctly.
When the script was created, did you choose an encoding, or accept the default? If the later, you need to find out which encoding was used. UTF-8 is likely.
However, in this case, the character may not be a mis-representation. Unicode replacement character explains that this character is used as a replacement for some other character that cannot be represented. It's possible in your case that the code you are looking at is simply saying, if we have some data that could not be represented, treat it as a hyphen instead. In other words, this may be nothing to do with the script generation/viewing process, but rather a deliberate piece of code.

Converting a Postgresql database from SQL_ASCII, containing mixed encoging types, to UTF-8

I have a postgresql database I would like to convert to UTF-8.
The problem is that it is currently SQL_ASCII, so hasn't been doing any kind of encoding conversion on its input, and as such has ended up with data of a mix of encoding types in the tables. One row might contain values encoded as UTF-8, another might be ISO-8859-x, or Windows-125x, etc.
This has made performing a dump of the database, and converting it to UTF-8 with the intention of importing it into a fresh UTF-8 database, difficult. If the data were all of one encoding type, I could just run the dump file through iconv, but I don't think that approach works here.
Is the problem fundamentally down to knowing how each data is encoded? Here, where that is not known, can it be worked out, or even guessed? Ideally I'd love a script which would take a file, any file, and spit out valid UTF-8.
This is exactly the problem that Encoding::FixLatin was written to solve*.
If you install the Perl module then you'll also get the fix_latin command-line utility which you can use like this:
pg_restore -O dump_file | fix_latin | psql -d database
Read of the 'Limitations' section of the documentation to understand how it works.
[*] Note I'm assuming that when you say ISO-8859-x you mean ISO-8859-1 and when you say CP125x you mean CP1252 - because the mix of ASCII, UTF-8, Latin-1 and WinLatin-1 is a common case. But if you really do have a mixture of eastern and western encodings then sorry but you're screwed :-(
It is impossible without some knowledge of the data first. Do you know if it is a text message or people's names or places? In some particular language?
You can try to encode a line of a dump and apply some heuristic — for example try an automatic spell checker and choose an encoding that generates the lowest number of errors or the most known words etc.
You can use for example aspell list -l en (en for English, pl for Polish, fr for French etc.) to get a list of misspelled words. Then you can choose encoding which generates the least of them. You'd need to install corresponding dictionary package, for example "aspell-en" in my Fedora 13 Linux system.
I've seen exactly this problem myself, actually. The short answer: there's no straightforward algorithm. But there is some hope.
First, in my experience, the data tends to be:
99% ASCII
.9% UTF-8
.1% other, 75% of which is Windows-1252.
So let's use that. You'll want to analyze your own dataset, to see if it follows this pattern. (I am in America, so this is typical. I imagine a DB containing data based in Europe might not be so lucky, and something further east even less so.)
First, most every encoding out there today contains ASCII as a subset. UTF-8 does, ISO-8859-1 does, etc. Thus, if a field contains only octets within the range [0, 0x7F] (ie, ASCII characters), then it's probably encoded in ASCII/UTF-8/ISO-8859-1/etc. If you're dealing with American English, this will probably take care of 99% of your data.
On to what's left.
UTF-8 has some nice properties, in that it will either be 1 byte ASCII characters, OR everything after the first byte will be 10xxxxxx in binary. So: attempt to run your remaining fields through a UTF-8 decoder (one that will choke if you give it garbage.) On the fields it doesn't choke on, my experience has been that they're probably valid UTF-8. (It is possible to get a false positive here: we could have a tricky ISO-8859-1 field that is also valid UTF-8.)
Last, if it's not ASCII, and it doesn't decode as UTF-8, Windows-1252 seems to be the next good choice to try. Almost everything is valid Windows-1252 though, so it's hard to get failures here.
You might do this:
Attempt to decode as ASCII. If successful, assume ASCII.
Attempt to decode as UTF-8.
Attempt to decode as Windows-1252
For the UTF-8 and Windows-1252, output the table's PK and the "guess" decoded text to a text file (convert the Windows-1252 to UTF-8 before outputting). Have a human look over it, see if they see anything out of place. If there's not too much non-ASCII data (and like I said, ASCII tends to dominate, if you're in America...), then a human could look over the whole thing.
Also, if you have some idea about what your data looks like, you could restrict decodings to certain characters. For example, if a field decodes as valid UTF-8 text, but contains a "©", and the field is a person's name, then it was probably a false positive, and should be looked at more closely.
Lastly, be aware that when you change to a UTF-8 database, whatever has been inserting this garbage data in the past is probably still there: you'll need to track down this system and teach it character encoding.
I resolved using this commands;
1-) Export
pg_dump --username=postgres --encoding=ISO88591 database -f database.sql
and after
2-) Import
psql -U postgres -d database < database.sql
these commands helped me solve the problem of conversion SQL_ASCII - UTF-8

best character set and collation for European based website

I am going to be building a application which will be used by people all over Europe. I need to know which collation and character set would be best suited for user inputted data. Or should I make a separate table for each language. A article to something explaining this would be great.
Thanks :)
Character set, without doubt, UTF-8. Collation, I am not sure there is a good answer to that, but you might want to read this report.
Unicode is a very large character set including nearly all characters from nearly all languages.
There are a number of ways to store Unicode text as a sequence of bytes - these ways are called encodings. All Unicode encodings (well, all complete Unicode encodings) can store all Unicode text as a sequence of bytes, in some format - but the number of bytes that any given piece of text takes will depend on the encoding used.
UTF-8 is a Unicode encoding that is optimized for English and other languages which use very few characters outside the Latin alphabet. UTF-16 is a Unicode encoding which is possibly more appropriate for text in a variety of European languages. Java and .NET store all text in-memory (the String class) as UTF-16 encoded Unicode.