I recently looked at some vba source at Microsoft: [Convert Fractions to Decimal Values][1]
[1]: https://support.microsoft.com/en-us/kb/185424 and I noticed that several functions had a trailing "$", specifically trim$(), left$(), and mid$(). My question is: what does the "$" signify?
I downloaded the microsoft function and it ran correctly under Excel 2007.
Since VBA trim() works differently from the worksheet function trim(), I wrote a small program to compare the operation of the 3 possible trim() calls. I found that trim() and trim$() produced identical output. worksheetfunction.trim(), of course, produces output that has extraneous space characters removed from inside the string.
I am very curious about the trailing "$", and will be grateful for enlightenment!
Thank you,
Dave
To quote from https://bytes.com/topic/access/answers/196893-difference-between-left-left-function
Allen Browne
The trailing $ is a type declaration character for the String data type in
VBA.
The result returned from Left$() is a string, whereas Left() returns a
Variant.
You must use Left(), not Left$() if there is any chance of Null values,
since the Variant can be Null but the String cannot.
That post has a full worked example
The syntax is a left-over habit from ancient history. In early versions of Basic variables did not have to be declared but data types were implied by the name of the variable. Any variable ending with $ was a string and any variable ending with % was an integer.
FORTRAN had a similar convention: any variable starting with the letters I, J, K, L, M or N were integers, all others were real.
Related
When I write a hex value in my VB.NET code, I want it to look like this:
&H0F (Binary: &B00001111)
but instead, Visual Studio makes it (imo) unreadable by removing the leading 0's:
&HF (Binary: &B1111)
That way, I cant see easily whether it's a byte, a short, etc.
So my question is: Is there a setting in the Visual Studio IDE that disables this "feature"?
I really want to keep those 0's.
Thank you in advance!
In VS2017 and above: if you use the group separator _ (underscore character), the leading zeros will not be removed by the editor. See: Hexadecimal, binary, and octal literals
Note that the group separator adds no intrinsic meaning to value; they are just meaningless formatting characters . What I mean by that is that only the digits are preserved when it is evaluated by the parser. Think of it as all "_" are removed from the string before evaluating. So, &B1_1_1_1 is the same as &B1________________1_1_1.
Some Examples:
Dim b As Byte
b = &B0000_1111
b = &B0_0_0_0_1_1_1_1
b = &H0_F
The IBM i implementation of regex uses apostrophes (instead of e.g. slashes) to delimit a regex string, i.e.:
... where REGEXP_SUBSTR(MYFIELD,'myregex_expression')
If I try to use an apostrophe inside a [group] within the expression, it always errors - presumably thinking I am giving a closing quote. I have tried:
- escaping it: \'
- doubling it: '' (and tripling)
No joy. I cannot find anything relevant in the IBM SQL manual or by google search.
I really need this to, for instance, allow names like O'Leary.
Thanks to Wiktor Stribizew for the answer in his comment.
There are a couple of "gotchas" for anyone who might land on this question with the same problem. The first is that you have to give the (presumably Unicode) hex value rather than the EBCDIC value that you would use, e.g. in ordinary interactive SQL on the IBM i. So in this case it really is \x27 and not \x7D for an apostrophe. Presumably this is because the REGEXP_ ... functions are working through Unicode even for EBCDIC data.
The second thing is that it would seem that the hex value cannot be the last one in the set. So this works:
^[A-Z0-9_\+\x27-]+ ... etc.
But this doesn't
^[A-Z0-9_\+-\x27]+ ... etc.
I don't know how to highlight text within a code sample, so I draw your attention to the fact that the hyphen is last in the first sample and second-to-last in the second sample.
If anyone knows why it has to not be last, I'd be interested to know. [edit: see Wiktor's answer for the reason]
btw, using double quotes as the string delimiter with an apostrophe in the set didn't work in this context.
A single quote can be defined with the \x27 notation:
^[A-Z0-9_+\x27-]+
^^^^
Note that when you use a hyphen in the character class/bracket expression, when used in between some chars it forms a range between those symbols. When you used ^[A-Z0-9_\+-\x27]+ you defined a range between + and ', which is an invalid range as the + comes after ' in the Unicode table.
Hi may i know what does the below query means?
REGEXP_REPLACE(number,'[^'' ''-/0-9:-#A-Z''[''-`a-z{-~]', 'xy') ext_number
part 1
In terms of explaining what the function function call is doing:
It is a function call to analyse an input string 'number' with a regex (2nd argument) and replace any parts of the string which match a specific string. As for the name after the parenthesis I am not sure, but the documentation for the function is here
part 2
Sorry to be writing a question within an answer here but I cannot respond in comments yet (not enough rep)
Does this regex work? Unless sql uses different syntax this would appear to be a non-functional regex. There are some red flags, e.g:
The entire regex is wrapped in square parenthesis, indicating a set of characters but seems to predominantly hold an expression
There is a range indicator between a single quote and a character (invalid range: if a dash was required in the match it should be escaped with a '\' (backslash))
One set of square brackets is never closed
After some minor tweaks this regex is valid syntax:
^'' ''\-\/0-9:-#A-Z''[''-a-z{-~]`, but does not match anything I can think of, it is important to know what string is being examined/what the context is for the program in order to identify what the regex might be attempting to do
It seems like it is meant to replaces all ASCII control characters in the column or variable number with xy.
[] encloses a class of characters. Any character in that class matches. [^] negates that, hence all characters match, that are not in the class.
- is a range operator, e.g. a-z means all characters from a to z, like abc...xyz.
It seams like characters enclosed in ' should be escaped (The second ' is to escape the ' in the string itself.) At least this would make some sense. (But for none of the DBMS I found having a regexp_replace() function (Postgres, Oracle, DB2, MariaDB, MySQL), I found something in the docs, that would indicate this escape mechanism. They all use \, but maybe I missed something? Unfortunately you didn't tag which DBMS you're actually using!)
Now if you take an ASCII table you'll see, that the ranges in the expression make up all printable characters (counting space as printable) in groups from space to /, 0 to 9, : to #, etc.. Actually it might have been shorter to express it as '' ''-~, space to ~.
Given the negation, all these don't match. The ones left are from NUL to US and DEL. These match and get replaced by xy one by one.
I have made a program which takes a 1000 digit number as input.
It is fixed, so I put this input into the code file itself.
I would obviously be storing it as Integer type, but how do I do it?
I have tried the program by having 1000 digits in the same line. I know this is the worst possible code format! But it works.
How can assign the variable this number, and split its lines. I read somewhere something about eos? Ruby, end of what?
I was thinking that something similar to comments could be used here.
Help will be appreciated.
the basic idea is to make this work:
a=3847981438917489137897491412341234
983745893289572395725258923745897232
instead of something like this:
a=3847981438917489137897491412341234983745893289572395725258923745897232
Haskell doesn't have a way to split (non-String) literals across multiple lines. Since Strings are an exception, we can shoehorn in other literals by parsing a multiline String:
v = read
"32456\
\23857\
\23545" :: Integer
Alternately, you can use list syntax if you think it's prettier:
v = read . concat $
["32456"
,"24357"
,"23476"
] :: Integer
The price you pay for this is that some work will be done (once) at runtime, namely, the parsing (e.g. read).
I have a Sql statament using special character (ex: ('), (/), (&)) and I don't know how to write them in my VB.NET code. Please help me. Thanks.
Find out the Unicode code point for the character (from http://www.unicode.org) and then use ChrW to convert from the code point to the character. (To put this in another string, use concatenation. I'm somewhat surprised that VB doesn't have an escape sequence, but there we go.)
For example, for the Euro sign (U+20AC) you'd write:
Dim euro as Char = ChrW(&H20AC)
The advantage of this over putting the character directly into source code is that your source code stays "just pure ASCII" - which means you won't have any strange issues with any other program trying to read it, diff it, etc. The disadvantage is that it's harder to see the symbol in the code, of course.
The most common way seems to be to append a character of the form Chr(34)... 34 represents a double quote character. The character codes can be found from the windows program "charmap"... just windows/Run... and type charmap
If you are passing strings to be processed as SQL statement try doubling the characters for example.
"SELECT * FROM MyRecords WHERE MyRecords.MyKeyField = ""With a "" Quote"" "
The '' double works with the other special characters as well.
The ' character can be doubled up to allow it into a string e.g
lSQLSTatement = "Select * from temp where name = 'fred''s'"
Will search for all records where name = fred's
Three points:
1) The example characters you've given are not special characters. They're directly available on your keyboard. Just press the corresponding key.
2) To type characters that don't have a corresponding key on the keyboard, use this:
Alt + (the ASCII code number of the special character)
For example, to type ¿, press Alt and key in 168, which is the ASCII code for that special character.
You can use this method to type a special character in practically any program not just a VB.Net text editor.
3) What you probably looking for is what is called 'escaping' characters in a string. In your SQL query string, just place a \ before each of those characters. That should do.
Chr() is probably the most popular.
ChrW() can be used if you want to generate unicode characters
The ControlChars class contains some special and 'invisible' characters, plus the quote - for example, ControlChars.Quote