var clientString = "{\"max\":1214.704958677686}";
JObject o = JObject.Parse(clientString);
var jsonString = o.ToString();
contents of jsonString:
{
"max": 1214.7049586776859
}
this is both in visualizing the object and in doing ToString(). Note that the 686 has mysteriously been expanded to 6859 (precision added). This is a problem for us because the numbers are not exactly the same, and a hash function over the json later does not match.
#Ilija Dimov is correct--JSON.NET parses JSON floats as doubles by default. If you still want to use JObject instead of creating a full blown POCO for deserialization, you can use a JsonTextReader and set the FloatParseHandling option:
var reader = new JsonTextReader(new StringReader(clientString));
reader.FloatParseHandling = FloatParseHandling.Decimal;
JObject obj = JObject.Load(reader);
Console.WriteLine(obj["max"].Value<decimal>()); // 1214.704958677686
The reason your value is changed is because of the nature of floating point numbers in .NET. The JObject.Parse(clientString) method at some point executes the following line:
double d;
double.TryParse("1214.704958677686", NumberStyles.Float | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out d);
where d represents the number that you get in the JObject.
As d is of type double and double is floating point number, you didn't get the value you expect. Read more about Binary floating point and .NET.
There is an option in JSON.NET for parsing floating point numbers as decimals and get the precision you need, but to do that you need to create custom class that matches your json string and deserialize the json. Something like this:
public class MyClass
{
[JsonProperty("max")]
public decimal Max { get; set; }
}
var obj = JsonConvert.DeserializeObject<MyClass>(clientString, new JsonSerializerSettings
{
FloatParseHandling = FloatParseHandling.Decimal
});
By using this code sample, the value of max property won't be changed.
You can experiment this behaviour just by parsing to float, double and decimal:
Assert.AreEqual(1214.705f,float.Parse("1214.704958677686"));
Assert.AreEqual(1214.7049586776859, double.Parse("1214.704958677686"));
Assert.AreEqual(1214.704958677686, decimal.Parse("1214.704958677686"));
So json.net is using double as an intermediate type. You can change this by setting FloatParseHandling option.
Related
I'm trying to convert a DateTime runtimetype value to Expression<DateTime, DateTimeType>. I've been trying to achieve this for almost three days now. I have tried different approaches but non is working.
The reason I want to achieve this is because moor_flutter library in some cases uses and accepts the library's custom runtimetypes on methods and and the parameter values on those methods.
Below is the sample code;
final DateTime dateToday = new DateTime.now(); // convert DateTime to Expression<DateTime, DateTimeType>
var dateWithNewRuntimetype; // assign the converted value to this variable
I thought I fixed this issue by adding as as Expression<DateTime, DateTimeType> to the value of dateWithNewRuntimetype variable value but no this is not the solution either.
The solution will work on the code below
Stream<List> getLoansWithTomorrowDueDate(int dayInFuture) {
return (select(loans)
..where((l) => l.due_date.isBetween(
dateToday, // it should be Expression<DateTime, DateTimeType> not DateTIme
futureDate, // it should be Expression<DateTime, DateTimeType> not DateTIme)))
.watch();
}
If you want me to provide more info on this I will do so.
Thank you, so much Love.
The isBetween is compared withSqlType.
You must use isBetweenValues.
/// Defines extension functions to express comparisons in sql
extension ComparableExpr<DT, ST extends ComparableType<DT>>
on Expression<DT, ST> {
Expression<bool, BoolType> isBetween(
Expression<DT, ST> lower, Expression<DT, ST> higher,
{bool not = false});
Expression<bool, BoolType> isBetweenValues(DT lower, DT higher,
{bool not = false});
}
A similar question to a previous one I asked, but the difference being that this not for direct rendering from an underlying field - it's instead part of a some SSJS.
This is for a view column which displays the result of a SSJS function, which returns HTML that gets rendered. This HTML includes a date from a DateTime field, which gets converted to text using #Text. The problem I have with this is, #Text converts dates using the locale settings of the server, not the browser.
Is there an alternative to #Text(dateValue,"D0S0") that's browser locale aware?
The most "XPagey" way to do this is to use a date/time converter. For example (using a stand-in for the computed value):
<xp:viewColumn columnName="">
<xp:this.value><![CDATA[#{javascript:
new java.util.Date()
}]]></xp:this.value>
<xp:this.converter>
<xp:convertDateTime type="both"/>
</xp:this.converter>
</xp:viewColumn>
That "convertDateTime", with its built-in formats, will respect the browser's provided locale. If you set the option in the Xsp Properties to use the browser's time zone and "Round trip", it should also respect the user's time zone.
I've managed to get round this by using DateFormat.getDateInstance. The only problem with this is it doesn't return a short date in the same format as the XPage date converter (no leading zeros and a 2-figure year). I've got round this though with some fiddling around with the string after.
Here's the full function:
function returnLocalShortDate(ndtDate) {
// Receives NotesDateTime object, Java date or string; returns localised date string in XPages short date format
importPackage(java.text);
if (#IsText(ndtDate)) { // string
var jsDate = #TextToTime(ndtDate);
} else if (ndtDate instanceof Date) { // Java date
var jsDate:Date = ndtDate;
} else if (#IsTime(ndtDate)) { // Notes date/time
var jsDate:Date = ndtDate[0].toJavaDate();
} else {
return("");
}
var strDate:String = java.text.DateFormat.getDateInstance(DateFormat.SHORT, context.getLocale()).format(jsDate);
var strYear = jsDate.getFullYear();
var strDateArray = strDate.split("/");
strDate = ('0' + strDateArray[0]).slice(-2) + '/' + ('0' + strDateArray[1]).slice(-2) + '/' + strYear;
return(strDate);
}
Actually, if you know the format you want, rather than what the user might want via their browser settings, you should use the SimpleDateFormatter class. You can supply the format in accordance with whatever pattern you want from the javadocs for that class. If you supply the NotesDocument object and the field name, this returns the date in dd-MMM-yyyy format.
function getFormattedDate ( doc:NotesDocument, fieldName:String ) {
importPackage(java.text);
var dateFormatter:java.text.SimpleDateFormat = new SimpleDateFormat("dd-MMM-yyyy");
var d:Date = new Date(#Today());
if ( doc.hasItem (fieldName) ) {
var valueVector:java.util.Vector = doc.getItemValueDateTimeArray(fieldName);
var iterator = valueVector.iterator();
while (iterator.hasNext()) {
var itemvalue = iterator.next();
if ((typeof(itemvalue)).endsWith("DateTime")) {
d = new Date(itemvalue.toJavaDate());
return dateFormatter.format(d);
}
}
} else {
return fieldName + " is not on the document"
}
}
I owe credit to Declan Lynch's blog entry on date formatting, which takes a little debugging because SSJS returns the date value as an Vector now.
Could someone explain why the FLEX 4.5 XMLDecoder does this to my XML-data?
var decoder:XMLDecoder = new XMLDecoder;
var $object:Object = decoder.decode( <xmltag>08.00</xmltag> );
// object = "08.00"
var decoder:XMLDecoder = new XMLDecoder;
var $object:Object = decoder.decode( <xmltag>11.00</xmltag> );
// Object = "11" (HEY! Where did my '.00' part of the string go?)
var decoder:XMLDecoder = new XMLDecoder;
var $object:Object = decoder.decode( <xmltag>11.30</xmltag> );
// Object = "11.3" (HEY! Where did my '0' part of the string go?)
The Flex deserializer also gave me issues with this. It may be interpreting them as Number objects and thus they will return short representations when toString() is called.
Try using .toFixed(2) whenever you need to print a value such as 11.00
var $object:Object = decoder.decode( <xmltag>11.00</xmltag> );
trace($object); //11
trace($object.toFixed(2)); //11.00
So, to the answer the original question of why this is happening:
In the source code for SimpleXMLDecoder (which I'm guessing has similar functionality to XMLDecoder), there's a comment in the function simpleType():
//return the value as a string, a boolean or a number.
//numbers that start with 0 are left as strings
//bForceObject removed since we'll take care of converting to a String or Number object later
numbers that start with 0 are left as strings - I guess they thought of phone numbers but not decimals.
Also, because of some hacky implicit casting, you actually have three different types -
"0.800" : String
11 : int
11.3: Number
In the big picture I want to create a frame based application in Bada that has a single UI control - a label. So far so good, but I want it to display a number of my choosing and decrement it repeatedly every X seconds. The threading is fine (I think), but I can't pass the label pointer as a class variable.
//MyTask.h
//...
result Construct(Label* pLabel, int seconds);
//...
Label* pLabel;
//MyTask.cpp
//...
result
MyTask::Construct(Label* pLabel, int seconds) {
result r = E_SUCCESS;
r = Thread::Construct(THREAD_TYPE_EVENT_DRIVEN);
AppLog("I'm in da constructor");
this->pLabel = pLabel;
this->seconds = seconds;
return r;
}
//...
bool
Threading::OnAppInitializing(AppRegistry& appRegistry)
{
// ...
Label* pLabel = new Label();
pLabel = static_cast<Label*>(pForm->GetControl(L"IDC_LABEL1"));
MyTask* task = new MyTask();
task->Construct(&pLabel); // HERE IS THE ERROR no matching for Label**
task->Start();
// ...
}
The problem is that I have tried every possible combination of *, &, and just plain pLabel, known in Combinatorics...
It is not extremely important that I get this (it is just for training) but I am dying to understand how to solve the problem.
Have you tried:
task->Construct(pLabel, 0);
And by that I want to point out that you are missing the second parameter for MyTask::Construct.
No, I haven't. I don't know of a second parameter. But this problem is solved. If I declare a variable Object* __pVar, then the constructor should be Init(Object* pVar), and if I want to initialize an instance variable I should write
Object* pVar = new Object();
MyClass* mClass = new MyClass();
mClass->Construct(pVar);
I want to combine two guid values and generate a 32 bit alphanumberic value(It can be done by using hashing).
Not Pretty, but it works..
private static Guid MungeTwoGuids(Guid guid1, Guid guid2)
{
const int BYTECOUNT = 16;
byte[] destByte = new byte[BYTECOUNT];
byte[] guid1Byte = guid1.ToByteArray();
byte[] guid2Byte = guid2.ToByteArray();
for (int i = 0; i < BYTECOUNT; i++)
{
destByte[i] = (byte) (guid1Byte[i] ^ guid2Byte[i]);
}
return new Guid(destByte);
}
and yes, I can deal with the non-unique-guarantee in my case
What about splitting the Guids into 2 chunks of 8 bytes each, convert them to ulong (8 bytes), XOR combine them and then concat the 2 results.
public static Guid Combine(this Guid x, Guid y)
{
byte[] a = x.ToByteArray();
byte[] b = y.ToByteArray();
return new Guid(BitConverter.GetBytes(BitConverter.ToUInt64(a, 0) ^ BitConverter.ToUInt64(b, 8))
.Concat(BitConverter.GetBytes(BitConverter.ToUInt64(a, 8) ^ BitConverter.ToUInt64(b, 0))).ToArray());
}
You can't convert 2 128-bit GUIDs into a 16-bit or 32-bit value and maintain uniqueness. For your stated application (use value in URL) this doesn't seem to make sense, as a given value in the URL could map to any number of GUID combinations. Have you considered this?
The best approach would be to use an URL-shortening lookup where you generate a unique ID and map it to the GUIDs if needed - similarly to bit.ly or tinyurl.com.
var a = Guid.NewGuid();
var b = Guid.NewGuid();
var hashOfXor = Xor(a, b).GetHashCode();
public static Guid Xor(Guid a, Guid b)
{
unsafe
{
Int64* ap = (Int64*) &a;
Int64* bp = (Int64*) &b;
ap[0] ^= bp[0];
ap[1] ^= bp[1];
return *(Guid*) ap;
}
}
I actually did have a need to merge two Guids together to create a third Guid.
Where the third Guid (not necessarily unique) would be the same regardless of the order the two original Guids were supplied.
So I came up with this:
public static Guid Merge(Guid guidA, Guid guidB)
{
var aba = guidA.ToByteArray();
var bba = guidB.ToByteArray();
var cba = new byte[aba.Length];
for (var ix = 0; ix < cba.Length; ix++)
{
cba[ix] = (byte)(aba[ix] ^ bba[ix]);
}
return new Guid(cba);
}
Assuming you want to generate a 32 byte value you can just concatenate the GUIDs since they are 16 byte each. If you really need a 32 bit value the only solution I see is generating your own 32 bit values and storing the related GUIDs in a database so you can retrieve them later.
In .NET Core 3 we can use Sse2/Span<T> to speed things up, and avoid all allocations. Essentially this code treats a Guid as 2 consecutive Int64 values, and performs the xor on them. SSE2 performs the xor in a single processor instruction (SIMD).
public static Guid Xor(this Guid a, Guid b)
{
if (Sse2.IsSupported)
{
var result = Sse2.Xor(Unsafe.As<Guid, Vector128<long>>(ref a), Unsafe.As<Guid, Vector128<long>>(ref b));
return Unsafe.As<Vector128<long>, Guid>(ref result);
}
var spanA = MemoryMarshal.CreateSpan(ref Unsafe.As<Guid, long>(ref a), 2);
var spanB = MemoryMarshal.CreateSpan(ref Unsafe.As<Guid, long>(ref b), 2);
spanB[0] ^= spanA[0];
spanB[1] ^= spanA[1];
return b;
}
Depends on the platform and details of what you are trying to do.
In .NET/C# you could jus take avery simple approach:
var result = g1.GetHashCode() ^ g2.GetHashCode();
I would use an UUID5 (name-based) to combine two GUIDs, see https://stackoverflow.com/a/5657517/7556646
Guid g1 = new Guid("6164742b-e171-471b-ad6f-f98a78c5557e");
Guid g2 = new Guid("acbc41aa-971c-422a-bd42-bbcefa32ffb4");
Guid g12 = Create(IsoOidNamespace, g1.ToString() + g2.ToString(), 5)
In this example g12 would be: e1ccaee5-ea5e-55c6-89a5-fac02043326e.
There's no native support in the .NET Framework for creating these, but the code is posted on GitHub that implements the algorithm.
See as well the following .NET Fiddle, https://dotnetfiddle.net/VgHLtz
Why not try a simple operator i.e. AND, OR, XOR etc. To combine the two. XOR would be your best bet hear I would imagine as it has the nice property of when xoring the result with either of the two inputs you will get the other.
Edit: having just looked at this solution, there is a problem with it. The values would have to be normalised. Take a look at Vinay's Answer for a better solution.
Here's a one-liner for you:
g1.ToByteArray().Concat(g2.ToByteArray()).GetHashCode()
public static string Merge(Guid one, Guid two)
{
return new List<Guid>() { one, two }
.OrderBy(x => x.GetHashCode())
.Select(y => y.ToString().ToLowerInvariant())
.Aggregate((a, b) => ${a.ToLowerInvariant()}_{b.ToLowerInvariant()}");
}
So in my situation i needed to maintain order in order to make sure that the 2 Guids could be merged regardless of order. Therefore they have to be ordered. That was step one. Then, it's simply selecting the guids to string and for consitency (super important), I used string.ToLowerInvariant(). Then concatenated them using the .Aggregate function.