Why does Microsoft tend to report "error codes" as hexadecimal values?
Error codes are 32-bit double word values (4 byte values.) This is likely the raw integer return code of whatever C-style function has reported an error.
However, why report the error to a user in hexadecimal? The "0x" prefix is worthless, and the savings in character length is minimal. These errors end up displayed to end users in Microsoft software and even on Microsoft websites.
For example:
0x80302010 is 10 characters long, and very cryptic.
2150637584 is the decimal equivalent, and much more user friendly.
Is there any description of the "standard" use of a 32-bit field as an error code mechanism (possibly dividing the field into multiple fields for developer interpretation) or of the logic behind presenting a hexadecimal code to end users?
We can only guess about the reason, so this question cannot be answered for sure. But let's guess:
One reason might be that with hex numbers, you know the number will have 8 digits. If it has more or less digits the number is "corrupt" (for example, the customer mistyped). With decimal numbers the number of digits for the same value varies.
Also, to a developer, hex numbers are more convenient and natural than decimal numbers. For example, if some info is coded as bit flags you can decipher them manually easily in hex numbers but not in decimal numbers.
It is a little bit subjective as to whether hexadecimal or decimal error codes are more user friendly. Here is a scenario where the hexadecimal error codes are significantly more convenient, which could be part of the reason that hexadecimal error codes are used in the first place.
Consider the documentation for Win32 Error Codes for Active Directory Service Interfaces, ADSI uses error codes with the format 0x8007XXXX, where the XXXX corresponds to a DWORD value that maps to a Win32 error code.
This makes it extremely easy to get the corresponding Win32 error code, because you can just strip off the last 4 digits. This would not be possible with a decimal error code representation.
The middle ground answer to this would be that formatting the number like an IPv4 address would be more luser-friendly while preserving some sort of formatting that helps the dev guys.
Although TBH I think hex is fine, the hypothetical non-technical user has no more idea what 0x1234ABCD means than 1234101112 or "Cracked gangle pin on fwip valve".
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…)
SBLineEntry is a proxy object in LLDB Python interface. SBLineEntry.GetColumn() returns point in a line, but I am not sure what it actually means.
In C++ side source, it resolves to LineEntry.column value, but it also lacks how it is measured in.
At first, I thought it as UTF-8 code unit offset. But it seems it isn't because when I measure it it looks like UTF-16 code unit offset. But I still couldn't find any definition for this value.
What is this value?
Raw byte offset in source code file?
UTF-8 code unit offset?
UTF-16 code unit offset?
Something else?
That's a good question! If the debug information is DWARF (except for Windows systems, it is), lldb is providing the DNS_LNS_set_column data from the DWARF line table as the number returned by SBLineEntry::GetColumn(). The DWARF5 specification doesn't say what this integer is counting -- it says only,
The DW_LNS_set_column opcode takes a single unsigned LEB128 operand and stores it in the column register of the state machine.
You're probably seeing that clang puts the UTF-16 code unit offset in the DWARF, but the standard doesn't require that. This would be a reasonable clarification request to file with the DWARF standards committee, http://dwarfstd.org
For the case of Rust programs, I think it's Unicode Scalar value offset.
Here's an open issue about column number. It says span_start function produces the column number.
span_start calls lookup_char_pos.
lookup_char_pos calls bytepos_to_file_charpos.
bytepos_to_file_charpos
They are repeating the word "char", and in Rust, "char" means Unicode Scalar Value.
I would like to determine the Thousand Separator used while running a VBA Code on a target machine without resolving to calling system built-in functions such as (Separator = Application.ThousandsSeparator).
I am using the following simple code using 'Format':
ThousandSeparator = Mid(Format(1000, "#,#"), 2, 1)
The above seems to work fine, and would like to confirm if this is a safe method of doing it without resorting to system calls.
I would expect the result to be a single char string in the form of , or . or ' or a Space as applicable to the locale on the machine.
Please note that I want to only use a language statement such as Format or similar (no sys calls). Also this relates to Thousands Separator not Decimal Separator. This article Using VBA to detect which decimal sign the computer is using does not help or answer my question. Thanks
Thanks in advance.
The strict answer to whether it is safe to use Format to get the thousands separator is No.
E.g. on Windows, it is possible to enter up to three characters into the Thousands Separator field in the regional settings in the control panel.
Suppose you enter asd and click OK.
If you now call Format(1000, "#,#") it will give you 1a000. That is only the first letter of your thousands separator. You have failed to retrieve it correctly.
Reading the registry:
? CreateObject("WScript.Shell").RegRead("HKCU\Control Panel\International\sThousand")
you get back asd in full.
To be fair, the Excel international properties do not seem to be of much help either. Application.International(xlThousandsSeparator) in this situation will return the separator originally defined in your computer's locale, not the value you've overridden it to.
Having that said, the practical answer is Yes, because it would appear (and if you happen to know for sure, please post an answer here) that there is no culture with multi-char thousand separator (even in China where scary things like 1億2345万6789 or 1億2345萬6789 exist, they happen to be represented with just one UTF-16 character), and you probably are happy to ignore the people who decided to play with their locale settings in that fashion.
When we are using cryptography always we are seeing byte arrays are being used instead of String values. But when we are looking at the techniques of most of the cryptography algorithms they uses hex values to do any operations. Eg. AES: MixColumns, SubBytes all these techniques(I suppose it uses) uses hex values to do those operations.
Can you explain how these byte arrays are used in these operations as hex values.
I have an assignment to develop a encryption algorithm , therefore any related sample codes would be much appropriate.
Every four digits of binary makes a hexadecimal digit, so, you can convert back and forth quite easily (see: http://en.wikipedia.org/wiki/Hexadecimal#Binary_conversion).
I don't think I full understand what you're asking, though.
The most important thing to understand about hexadecimal is that it is a system for representing numeric values, just like binary or decimal. It is nothing more than notation. As you may know, many computer languages allow you to specify numeric literals in a few different ways:
int a = 42;
int a = 0x2A;
These store the same value into the variable 'a', and a compiler should generate identical code for them. The difference between these two lines will be lost very early in the compilation process, because the compiler cares about the value you specified, and not so much about the representation you used to encode it in your source file.
Main takeaway: there is no such thing as "hex values" - there are just hex representations of values.
That all said, you also talk about string values. Obviously 42 != "42" != "2A" != 0x2A. If you have a string, you'll need to parse it to a numeric value before you do any computation with it.
Bytes, byte arrays and/or memory areas are normally displayed within an IDE (integrated development environment) and debugger as hexadecimals. This is because it is the most efficient and clear representation of a byte. It is pretty easy to convert them into bits (in his mind) for the experienced programmer. You can clearly see how XOR and shift works as well, for instance. Those (and addition) are the most common operations when doing symmetric encryption/hashing.
So it's unlikely that the program performs this kind of conversion, it's probably the environment you are in. That, and source code (which is converted to bytes at compile time) probably uses a lot of literals in hexadecimal notation as well.
Cryptography in general except hash functions is a method to convert data from one format to another mostly referred as cipher text using a secret key. The secret key can be applied to the cipher text to get the original data also referred as plain text. In this process data is processed in byte level though it can be bit level as well. The point here the text or strings which we referring to are in limited range of a byte. Example ASCII is defined in certain range in byte value of 0 - 255. In practical when a crypto operation is performed, the character is converted to equivalent byte and the using the key the process is performed. Now the outcome byte or bytes will most probably be out of range of human readable defined text like ASCII encoded etc. For this reason any data to which a crypto function is need to be applied is converted to byte array first. For example the text to be enciphered is "Hello how are you doing?" . The following steps shall be followed:
1. byte[] data = "Hello how are you doing?".getBytes()
2. Process encipher on data using key which is also byte[]
3. The output blob is referred as cipherTextBytes[]
4. Encryption is complete
5. Using Key[], a process is performed over cipherTextBytes[] which returns data bytes
6 A simple new String(data[]) will return string value of Hellow how are you doing.
This is a simple info which might help you to understand reference code and manuals better. In no way I am trying to explain you the core of cryptography here.
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).