I would like to enter empty in place of Zero in numeric. i dont want use strings.
In Numeric field we can enter only NAN or INF but i want enter Empty.
There is no such thing as an Empty value for floating-point numerics in LabVIEW, just as there is no such thing in C#, C++, Java, or C. They all use the same IEEE standard to define floating-point values.
I opened an idea for this on the Idea Exchange: Create an "Optional" input type wrapper in the style of C++17's std::optional.
It was largely rejected because it's not a suitably useful thing for general use, but some ideas as to how you might implement it yourself were discussed there (don't miss the second page).
Related
Long story short, I am trying to convert strings of hex values to signed 2's complement integers. I was able to do this in a single line of code in Swift, but for some reason I can't find anything analogous in Kotlin. String.ToInt or String.ToUInt just give the straight base 16 to base 10 conversion. That works for some positive values, but not for any negative numbers.
How do I know I want the signed 2's complement? I've used this online converter and according to its output, what I want is the decimal from signed 2's complement, not the straight base 16 to base 10 conversion that's easy to do by hand.
So, "FFD6" should go to -42 (correct, confirmed in Swift and C#), and "002A" should convert to 42.
I would appreciate any help or even any leads on where to look. Because yes I've searched, I've googled the problem a bunch and, no I haven't found a good answer.
I actually tried writing my own code to do the signed 2's complement but so far it's not giving me the right answers and I'm pretty at a loss. I'd really hope for a built in command that does it instead; I feel like if other languages have that capability Kotlin should too.
For 2's complement, you need to know how big the type is.
Your examples of "FFD6" and "002A" both have 4 hex digits (i.e. 2 bytes). That's the same size as a Kotlin Short. So a simple solution in this case is to parse the hex to an Int and then convert that to a Short. (You can't convert it directly to a Short, as that would give an out-of-range error for the negative numbers.)
"FFD6".toInt(16).toShort() // gives -42
"002A".toInt(16).toShort() // gives 42
(You can then convert back to an Int if needed.)
You could similarly handle 8-digit (4-byte) values as Ints, and 2-digit (1-byte) values as Bytes.
For other sizes, you'd need to do some bit operations. Based on this answer for Java, if you have e.g. a 3-digit hex number, you can do:
("FD6".toInt(16) xor 0x800) - 0x800 // gives -42
(Here 0x800 is the three-digit number with the top bit (i.e. sign bit) set. You'd use 0x80000 for a five-digit number, and so on. Also, for 9–16 digits, you'd need to start with a Long instead of an Int. And if you need >16 digits, it won't fit into a Long either, so you'd need an arbitrary-precision library that handled hex…)
A vendor I use packages their software with AssemblyScript. They provide some infrastructure and I build on top of it.
Accidentally, I changed my double equal signs ("==") to triple equal signs ("===") in a function that performs equality checks on hexadecimal strings. I spent hours ensuring that the values checked are indeed equal and have the same case sensitivity, but nothing could make the if statement enter the branch I was expecting it to enter, except for going back to "==".
And so I ended up here, asking for help. How is "===" different to "==" in AssemblyScript? Is it some quirk of the language itself or the vendor's parser?
Yes. In AssemblyScript tripple equal ("===") compare raw references and skip overloading operator ("=="). See docs.
There are have proposal avoid this non-standard for TypeScript behaviour. You could check and upvote this issue
I am trying to display always-signed integers ('-1', '+4', etc: I'll even accept '+0') in OpenOffice Calc. I've had trouble finding exact information on the numeric formatting language used.
=TEXT(cellref;"#0")
doesn't display '+', and using "+#0" always displays '+' (it displays '-+3' for -3 in fact.)
Is there a format code for this, or do I have to write a function to handle the cases?
Here is a short but cryptic solution:
=TEXT(cellref;"\+#;\-#;0")
This is actually a three-part format code. It adds either a plus sign \+# for positive numbers, a minus sign \-# for negative numbers, or just a plain 0 for zeroes.
The syntax is described here: https://help.libreoffice.org/5.2/Common/Number_Format_Codes#Positive_and_Negative_Numbers
Another approach is to apply custom formatting, which is generally a good idea where numbers are involved, to make calculations with them easier:
"+"#;"-"#;0;General
What is the reasoning for parsing an integer? For instance, Integer.Parse('variable'.text)
I see this a lot and while manipulating data for a calculator I am building I found that Val('variable'.text) was all I need to use "numeric" values.
So, my question is how does Integer.Parse() help me with regards to calculators?
Thanks!
I found that "Val('variable'.text)" was all I need
If that's the case then go ahead and use Val(). But be aware that it behaves differently than .Parse() (or, often preferably, .TryParse()) methods.
For example, what do you want to do if the user inputs "123 isn't 456"? Val() will (I think) return:
123 As Double
Or how about the input "123 456"? That would be:
123456 As Double
Do you want it to be a Double? Do you want it to throw an error because it's not purely numeric? Something else? The behavior you want should be reflected in the code you write. Use Val() for one set of behaviors, .Parse() for another.
This should be an easy one for folks. Google's got nothing except content farms linking to one blurb, and that's written in broken English. So let's get this cleared up here where it'll be entombed for all time.
What's the trailing ampersand on VB hexadecimal numbers for? I've read it forces conversion to an Int32 on the chance VB wants to try and store as an Int16. That makes sense to me. But the part I didn't get from the blurb was to always use the trailing ampersand for bitmasks, flags, enums, etc. Apparantly, it has something to do with overriding VB's fetish for using signed numbers for things internally, which can lead to weird results in comparisons.
So to get easy points, what are the rules for VB.Net hexadecimal numbers, with and without the trailing ampersand? Please include the specific usage in the case of bitmasks/flags and such, and how one would also use it to force signed vs. unsigned.
No C# please :)
Vb.net will regard "&h"-notation hex constants in the range from 0x80000000-0xFFFFFFFF as negative numbers unless the type is explicitly specified as UInt32, Int64, or UInt64. Such behavior might be understandable if the numbers were written with precisely eight digits following the "&", but for some reason I cannot fathom, vb.net will behave that way even if the numbers are written with leading zeroes. In present versions of VB, one may force the number to be evaluated correctly by using a suffix of "&" suffix (Int64), "L" (Int64), "UL" (UInt64), or "UI" (UInt32). In earlier versions of VB, the "problem range" was 0x8000-0xFFFF, and the only way to force numbers in that range to be evaluated correctly (as a 32-bit integer, which was then called a "Long") was a trailing ampersand.
Visual Basic has the concept of Type Characters. These can be used to modify variable declarations and literals, although I'd not recommend using them in variable declarations - most developers are more familiar these days with As. E.g. the following declarations are equivalent:
Dim X&
Dim X As Long
But personally, I find the second more readable. If I saw the first, I'd actually have to go visit the link above, or use Intellisense, to work out what the variable is (not good if looking at the code on paper).