As you may be able to see in the image, I have a User model and #user.zip is stored as an integer for validation purposes (ie, so only digits are stored, etc.). I was troubleshooting an error when I discovered that my sample zip code (00100) was automatically being converted to binary, and ending up as the number 64.
Any ideas on how to keep this from happening? I am new to Rails, and it took me a few hours to figure out the cause of this error, as you might imagine :)
I can't imagine any other information would be helpful here, but please inform me if otherwise.
This is not binary, this is octal.
In Ruby, any number starting with 0 will be treated as an octal number. You should check the Ruby number literals to learn more about this, here's a quote:
You can use a special prefix to write numbers in decimal, hexadecimal, octal or binary formats. For decimal numbers use a prefix of 0d, for hexadecimal numbers use a prefix of 0x, for octal numbers use a prefix of 0 or 0o, for binary numbers use a prefix of 0b. The alphabetic component of the number is not case-sensitive.
For your case, you should not store zipcodes as numbers. Not only in the database, but even as variables don't treat them as numeric values. Instead, store and treat them as strings.
The zip should probably be stored as a string since you can't have a valid integer with leading zeroes.
Related
I have been wondering what this is actually called for a long time because a while ago (like 3 years ago) I thought it was called bytecode but since then I have realized what bytecode actually is. I'll give an example because I don't really know what to call it.
It looks like this:
\234\22\21\65\22\76\54\87. It's basically the byte of all the characters preceded by a backslash.
Does anyone know what this is called?
Thanks.
From the Lua reference manual:
We can specify any byte in a short literal string by its numeric value
(including embedded zeros). This can be done with the escape sequence
\xXX, where XX is a sequence of exactly two hexadecimal digits, or
with the escape sequence \ddd, where ddd is a sequence of up to three
decimal digits. (Note that if a decimal escape sequence is to be
followed by a digit, it must be expressed using exactly three digits.)
Also refer to https://en.wikipedia.org/wiki/String_literal#Escape_sequences
i am trying to check if a string is empty by doing the following
if trim(somestring) = '' then
begin
//that an empty string
end
i am doing this empty check in my client application , but i notice that some clients inserts empty strings even with this check applied .
on my Linux server side those empty chars showing as squares and when i copy those chars i can be able to bypass the empty string check like the follwing example
if you copy this empty chars the check will not be effected how can i avoid that ?
Your code is working correctly and the strings are not empty. An empty string is one whose length is zero, it has no characters. You refer to empty characters, but there is no such thing. When. your system displays a small empty square that indicates that the chosen font has no glyph for that character.
Let us assume that these strings are invalid. In that case the real problem you have is that you don't yet fully understand what properties are required for a string to be valid. Your code is written assuming that a string is valid if it contains at least one character with ordinal value greater than 32. Clearly that test is not correct. You need to step back and work out the precise rules for validity. Only when these are clear in your mind can you correct you program and check for validity correctly.
On the other hand perhaps these strings are valid and the mistake is simply that you are erroneously determining otherwise when you inspect the data. Only you can know this, we don't have the information.
A useful technique in all of this is to inspect the ordinal values of the strings. Loop through the characters printing the ordinal value of each one. That allows you to see what is really there and not be at the mercy of non-printing characters, characters with no glyph, invalid encodings, etc.
Since Trim is pretty simple function, it omits only characters with less than or equal dec 32 in ASCII table
( Sample from System.SysUtils.pas )
while S.Chars[L] <= ' ' do Dec(L);
Therefore it's possible that You just can't see some exotic chars ( > ASCII 128) due to bad encoding used with Your input string.
try to use :
StrToInt(Ord(SomeChar))
On every char that is not "trimmed" and remove them by hand or check Your encoding.
Kind Regards
Lets say I have a massive string of just a single character say x. I need to use huffman encoding.
A huffman encoding is a fully binary tree. So how does one create a huffman code for just a single character when we dont need two leaves at all ?
jbr's answer is fine; this is just a longer version of it.
Huffman is meant to produce a minimal-length sequence of bits that contains all the information in the original sequence of symbols, assuming that the decoder already knows the set of symbols. If there's only one symbol, the input data contains no information except its length.
In Huffman-based data formats, length is usually encoded separately, not as part of the Huffman-encoded bit sequence itself. The decoder of a single-symbol Huffman code therefore has all the information it needs to reconstruct the input without needing to read anything from the Huffman-encoded bit sequence. it is logical, then, that the Huffman encoder's output should be 0 bits long.
If you don't have a length encoded separately, then you must have a symbol to represent End Of Sequence so the decoder knows when to stop reading. Then your Huffman tree will have 2 nodes and you won't run into this special case.
If you only have one symbol, then you only need 1 bit per symbol. So you really don't have to do anything except count the number of bits and translate each into your symbol.
You simply could add an edge case in your code.
For example:
check if there is only one character in your hash table, which returns only the root of the tree without any leafs. In this case, you could add a code for this root node in your encoding function, like 0.
In the encoding function, you should refer to this edge case too.
In EDIFACT there are numeric data elements, specified e.g. as format n..5 -- we want to store those fields in a database table (with alphanumeric fields, so we can check them). How long must the db-fields be, so we can for sure store every possible valid value? I know it's at least two additional chars (for decimal point (or comma or whatever) and possibly a leading minus sign).
We are building our tables after the UN/EDIFACT standard we use in our message, not the specific guide involved, so we want to be able to store everything matching that standard. But documentation on the numeric data elements isn't really straightforward (or at least I could not find that part).
Thanks for any help
I finally found the information on the UNECE web site in the documentation on UN/EDIFACT rules Part 4. UN/EDIFACT rules Chapter 2.2 Syntax Rules . They don't say it directly, but when you put all the parts together, you get it. See TOC-entry 10: REPRESENTATION OF NUMERIC DATA ELEMENT VALUES.
Here's what it basically says:
10.1: Decimal Mark
Decimal mark must be transmitted (if needed) as specified in UNA (comma or point, put always one character). It shall not be counted as a character of the value when computing the maximum field length of a data element.
10.2: Triad Seperator
Triad separators shall not be used in interchange.
10.3: Sign
[...] If a value is to be indicated to be negative, it shall in transmission be immediately preceded by a minus sign e.g. -112. The minus sign shall not be counted as a character of the value when computing the maximum field length of a data element. However, allowance has to be made for the character in transmission and reception.
To put it together:
Other than the digits themselves there are only two (optional) chars allowed in a numeric field: the decimal seperator and a minus sign (no blanks are permitted in between any of the characters). These two extra chars are not counted against the maximum length of the value in the field.
So the maximum number of characters in a numeric field is the maximal length of the numeric field plus 2. If you want your database to be able to store every syntactically correct value transmitted in a field specified as n..17, your column would have to be 19 chars long (something like varchar(19)). Every EDIFACT-message that has a value longer than 19 chars in a field specified as n..17 does not need to be stored in the DB for semantic checking, because it is already syntactically wrong and can be rejected.
I used EDI Notepad from Liaison to solve a similar challenge. https://liaison.com/products/integrate/edi/edi-notepad
I recommend anyone looking at EDI to at least get their free (express) version of EDI Notepad.
The "high end" version (EDI Notepad Productivity Suite) of their product comes with a "Dictionary Viewer" tool that you can export the min / max lengths of the elements, as well as type. You can export the document to HTML from the Viewer tool. It would also handle ANSI X12 too.
I have a stored procedure for SQL 2000 that has an input parameter with a data type of varchar(17) to handle a vehicle identifier (VIN) that is alphanumeric. However, whenever I enter a value for the parameter when executing that has a numerical digit in it, it gives me an error. It appears to only accept alphabetic characters. What am I doing wrong here?
Based on comments, there is a subtle "feature" of SQL Server that allows letters a-z to be used as stored proc parameters without delimiters. It's been there forever (since 6.5 at least)
I'm not sure of the full rules, but it's demonstrated in MSDN (rename SQL Server etc): there are no delimiters around the "local" parameter. And I just found this KB article on it
In this case, it could be starting with a number that breaks. I assume it works for a contained number (but as I said I'm not sure of the full rules).
Edit: confirmed by Martin as "breaks with leading number", OK for "containing number"
This doesn't help much, but somewhere, you have a bug, typo, or oversight in your code. I spent 2+ years working with VINs as parameters, and other than regretting not having made it char(17) instead ov varchar(17), we never had any problems passing in alphanumeric VIN values. Somewhere, and I'd guess it's in the application layer, something is not liking digits -- perhaps a filter looking for only alphabetical characters?