double

问题 I'm hoping you can help with a bit of a head scratcher. I have written out a template class to calculate standard deviations: template <class T> double GetStandardDeviation(T* valueArray, int populationSize) { double average; T cumulativeValue = 0; double cumulativeSquaredDeviation = 0; // calculate average for (int i = 0; i < populationSize; i++) { cumulativeValue += valueArray[i]; } average = (double)cumulativeValue / (double)populationSize; // calculate S.D. for (int i = 0; i <

问题 I use ReShaper and when I compare two double values with ==, it suggests that I should use the Math. ABS method with a tolerance. See: https://www.jetbrains.com/help/resharper/2016.2/CompareOfFloatsByEqualityOperator.html This example double d = 0.0; double d2 = 0.0; if (d == d2) { /* some code */ } is then converted to double d = 0.0; double d2 = 0.0; if (Math.Abs(d - d2) < TOLERANCE) { /* some code */ } But I think it's really complicated for a developer to think about the right tolerance.

问题 I have this class to get data from Firestore: struct Spty: Identifiable{ var id: String var spty: String var r: NSNumber var g: NSNumber var b: NSNumber } class SptyViewModel: NSObject, ObservableObject{ @Published var specialities = [Spty]() @Published var search = "" func fetchData(){ let db = Firestore.firestore() db.collection("specialities").addSnapshotListener { (querySnapshot, error) in guard let documents = querySnapshot else {return } self.specialities = documents.documents

问题 I have this class to get data from Firestore: struct Spty: Identifiable{ var id: String var spty: String var r: NSNumber var g: NSNumber var b: NSNumber } class SptyViewModel: NSObject, ObservableObject{ @Published var specialities = [Spty]() @Published var search = "" func fetchData(){ let db = Firestore.firestore() db.collection("specialities").addSnapshotListener { (querySnapshot, error) in guard let documents = querySnapshot else {return } self.specialities = documents.documents

问题 I'm writing an extension to a FloatingPoint protocol. I want to cast it to a Double in any possible way. extension FloatingPoint { var toDouble: Double { return Double(exactly: self) ?? 0 //compile error } } I'd prefer not to tell what I'm trying to achieve so we can focus just on above problem. I'd prefer to hear that's impossible to do it this way instead of receiving a valid workaround for the bigger problem I'm trying to solve. I tried to use different Double constructors but maybe I wasn

问题 I'm writing an extension to a FloatingPoint protocol. I want to cast it to a Double in any possible way. extension FloatingPoint { var toDouble: Double { return Double(exactly: self) ?? 0 //compile error } } I'd prefer not to tell what I'm trying to achieve so we can focus just on above problem. I'd prefer to hear that's impossible to do it this way instead of receiving a valid workaround for the bigger problem I'm trying to solve. I tried to use different Double constructors but maybe I wasn

问题 I want to write code that, if I input a decimal number like 612.216, I can print it as a 612216 (actually convert it to integer). However, the program changes my number to something like 2162160000000000000000001 and I don't what to do about it. This is my code: #include <stdio.h> #include <math.h> int main() { long double x; scanf_s("%Lf", &x); while (floor(x)!=x) x = x * 10; printf("%Lf", x); return 0;} 回答1: How about this: #include <stdio.h> int main() { double number = 612.216; char

问题 I want to write code that, if I input a decimal number like 612.216, I can print it as a 612216 (actually convert it to integer). However, the program changes my number to something like 2162160000000000000000001 and I don't what to do about it. This is my code: #include <stdio.h> #include <math.h> int main() { long double x; scanf_s("%Lf", &x); while (floor(x)!=x) x = x * 10; printf("%Lf", x); return 0;} 回答1: How about this: #include <stdio.h> int main() { double number = 612.216; char

问题 I want to write code that, if I input a decimal number like 612.216, I can print it as a 612216 (actually convert it to integer). However, the program changes my number to something like 2162160000000000000000001 and I don't what to do about it. This is my code: #include <stdio.h> #include <math.h> int main() { long double x; scanf_s("%Lf", &x); while (floor(x)!=x) x = x * 10; printf("%Lf", x); return 0;} 回答1: How about this: #include <stdio.h> int main() { double number = 612.216; char

问题 When I run the following code in VC++ 2013 (32-bit, no optimizations): #include <cmath> #include <iostream> #include <limits> double mulpow10(double const value, int const pow10) { static double const table[] = { 1E+000, 1E+001, 1E+002, 1E+003, 1E+004, 1E+005, 1E+006, 1E+007, 1E+008, 1E+009, 1E+010, 1E+011, 1E+012, 1E+013, 1E+014, 1E+015, 1E+016, 1E+017, 1E+018, 1E+019, }; return pow10 < 0 ? value / table[-pow10] : value * table[+pow10]; } int main(void) { double d = 9710908999.008999; int j