I have following problem. I want to convert an integer value or float value into an byte array. Normaly I use the BitConverter.GetBytes() method.
int i = 10;
float a = 34.5F;
byte[] arr;
arr = BitConverter.GetBytes(i);
arr = BitConverter.GetBytes(a);
Is there a possibility to do this with implicit/explicit methods??
arr = i;
arr = a;
and also the other way around??
i = arr;
a = arr;
You can do it through an intermediate class. The compiler won't do two implicit casts by itself, so you must do one explicit cast and then the compiler will figure out the second one.
The problem is that with implicit casts, you must either cast to or from the type you declare the cast in, and you cannot inherit from sealed classes like 'int'.
So, it is not elegant at all. Extension methods are probably more elegant.
If you declare the class below, you can then do things like:
byte[] y = (Qwerty)3;
int x = (Qwerty) y;
public class Qwerty
{
private int _x;
public static implicit operator byte[](Qwerty rhs)
{
return BitConverter.GetBytes(rhs._x);
}
public static implicit operator int(Qwerty rhs)
{
return rhs._x;
}
public static implicit operator Qwerty(byte[] rhs)
{
return new Qwerty {_x = BitConverter.ToInt32(rhs, 0)};
}
public static implicit operator Qwerty(int rhs)
{
return new Qwerty {_x = rhs};
}
}
you could create extension methods to clean up the calling code a little bit - so you'd end up with:
int i = 10;
float a = 34.5F;
byte[] arr;
arr = i.ToByteArray();
arr = a.ToByteArray();
The code for the extension methods would be something like:
public static class ExtensionMethods
{
public static byte[] ToByteArray(this int i)
{
return BitConverter.GetBytes(i);
}
public static byte[] ToByteArray(this float a)
{
return BitConverter.GetBytes(a);
}
}
Related
I am wrapping some C++ code in managed C++ to access it in C#: I can not figure out how to make operators properly work in C#
I create in managed C++:
public ref class ClassCLI
{
public:
double val;
ClassCLI() {};
void operator ++() { val++; };
double% operator[](int i) { return val; }
};
This works in managed C++:
ClassCLI^ obj = gcnew ClassCLI();
obj++;
obj[0] = 12.0;
But in C#, I can not use the operators ++ or [] directly, I have to use some ugly name that defeats the purpose of operators.
var obj = new ClassCLI();
obj.op_Increment();
obj.op_Subscript(0) = 12.0;
Can one tell me what I am doing wrong ? I says on some posts that operators should be static for C#, it is easy for operator++ but not sure how to do for the operator[]
If you refer to
C++/CLI: how to overload an operator to accept reference types?
How to declare the default indexed property in C++/CLI interface
you can get an idea to implement your ClassCLI class.
Sample implementation:
C++
public ref class ClassCLI
{
public:
double val;
ClassCLI() {};
property double default[int]
{
double get(int index) { return val; }
void set(int index, double value) { val = value; }
}
static ClassCLI^ operator ++(ClassCLI^ c)
{
c->val++;
return c;
};
};
C#:
static void Main()
{
ClassCLI c = new ClassCLI();
Console.WriteLine(c.val);
c++;
Console.WriteLine(c.val);
c[0] = 12;
Console.WriteLine(c.val);
Console.Read();
}
Output:
0
1
12
Updated: How could I make a method with two paramerters to take any primitive number type, like int, uint, float, double, etc, (except bool)?
I'm currently using an object, but that means the method can accept any type.
public int[] MyNumberMethod(object a, object b)
{
if (a is int || a is uint || a is short || a is ushort || a is long || a is ulong || a is byte || a is sbyte || a is float || a is double || a is decimal)
{
if (b is int || b is uint || b is short || b is ushort || b is long || b is ulong || b is byte || b is sbyte || b is float || b is double || b is decimal)
return new int[] { Convert.ToInt32(b), Convert.ToInt32(a) };
}
return new int[] { 0, 0 };
}
This might not be as good as the other answers, but another option is to create your own structure where you only allow a value of certain data types:
public struct Number
{
#region Static methods and fields
private static readonly Type[] allowedTypes = new Type[] {
typeof(int), typeof(uint), typeof(short), typeof(ushort),
typeof(long), typeof(ulong), typeof(byte), typeof(sbyte),
typeof(float), typeof(double), typeof(decimal)
};
private static void CheckIsNumber(dynamic val) {
if (Array.IndexOf(allowedTypes, val.GetType()) == -1) { throw new InvalidCastException("Input type must be a number."); }
}
#endregion
#region Constructor
public Number(dynamic Value) {
Number.CheckIsNumber(Value);
_value = Value;
}
#endregion
#region Properties
private dynamic _value;
public dynamic Value {
get { return _value; }
set {
Number.CheckIsNumber(value);
_value = value;
}
}
#endregion
#region Overridden methods
public override bool Equals(object obj) { return _value.Equals(obj); }
public override int GetHashCode() { return _value.GetHashCode(); }
public override string ToString() { return _value.ToString(); }
#endregion
#region Conversion operators - Number
public static implicit operator Number(uint val) { return new Number(val); }
public static implicit operator Number(short val) { return new Number(val); }
public static implicit operator Number(ushort val) { return new Number(val); }
public static implicit operator Number(long val) { return new Number(val); }
public static implicit operator Number(ulong val) { return new Number(val); }
public static implicit operator Number(byte val) { return new Number(val); }
public static implicit operator Number(float val) { return new Number(val); }
public static implicit operator Number(double val) { return new Number(val); }
public static implicit operator Number(decimal val) { return new Number(val); }
#endregion
#region Conversion operators - Misc. data types
public static implicit operator int(Number num) { return (int)num.Value; }
public static implicit operator uint(Number num) { return (uint)num.Value; }
public static implicit operator short(Number num) { return (short)num.Value; }
public static implicit operator ushort(Number num) { return (ushort)num.Value; }
public static implicit operator long(Number num) { return (long)num.Value; }
public static implicit operator ulong(Number num) { return (ulong)num.Value; }
public static implicit operator byte(Number num) { return (byte)num.Value; }
public static implicit operator sbyte(Number num) { return (sbyte)num.Value; }
public static implicit operator float(Number num) { return (float)num.Value; }
public static implicit operator double(Number num) { return (double)num.Value; }
public static implicit operator decimal(Number num) { return (decimal)num.Value; }
#endregion
}
Every time you change the value or create a new instance of the structure it will verify if the input value's data type matches any of the items in the allowedTypes array. If not it will throw an InvalidCastException.
I have also added conversion operators which will let you use this as a normal number, thus you can use it pretty much like you would use any other numerical data type:
Number myNum = 3.5;
myNum += 10.4;
double something = myNum - 6.0;
However keep in mind that you must add a decimal point when working with double, float, etc. or else it will assume that the number is an integer:
Number myNum = 3.5;
myNum -= 2;
MessageBox.Show(myNum.ToString()); //Shows "1" as the second line converts 'myNum' into an integer.
All that said, here's how you would use it for your method:
public int[] MyNumberMethod(Number a, Number b)
{
try {
return new int[] { Convert.ToInt32(b), Convert.ToInt32(a) };
}
catch(InvalidCastException) {
return new int[] { 0, 0 };
}
}
And thanks to the conversion operators you won't need to specify a (Number) conversion. For example:
byte myByte = 133;
//Unnecessary.
MyNumberMethod((Number)17.4, (Number)myByte);
//This works just as fine.
MyNumberMethod(17.4, myByte);
Well since you want to use all primitive types except the bool, how about that?
public int MyNumberMethod<T>(T number) where T : struct
{
if (!(number is bool) && number.GetType().IsPrimitive)
return Convert.ToInt32(number);
return 0;
}
e.g.
MyNumberMethod<short>(5);
All numeric types (except double and float) are implicitly convertible to decimal and float is implicitly convertible to double. So if you make overloads like:
Method(double, double)
Method(decimal, double)
Method(decimal,decimal)
Method(double, decimal)
Your method will be callable with any two numbers but only with any two numbers.
First you must call other function like GenericNumberMethod, that will contain the calling to MyNumberMethod. You must have for each data type an implementacion of GenericNumberMethod with the corresponding parameter
public int MyNumberMethod(object number) {
return Convert.ToInt32(number);
}
public int GenericNumberMethod(int number) {
return MyNumberMethod(number);
}
public int GenericNumberMethod(decimal number) {
return MyNumberMethod(number);
}
Code:
void Main()
{
C.F();
}
public class C
{
public static void F()
{
var a = new A { i = 1, d = 2.5m };
var b = new B(a);
I(b);
D(b);
}
static void I(int i) { Console.WriteLine("int is: " + i); }
static void D(decimal d) { Console.WriteLine("decimal is: " + d); }
}
public class A
{
public int i;
public decimal d;
}
public class B
{
A _a;
public B(A a) { _a = a; }
public static implicit operator int(B b) { return b._a.i; }
public static implicit operator decimal(B b) { return b._a.d; }
}
OUTPUT:
int is: 1
decimal is: 2.5
Comment out:
//public static implicit operator decimal(B b) { return b._a.d; }
OUTPUT:
int is: 1
decimal is: 1
What is going on when the second version runs and outputs 1 for both cases?
My guess is that the compiler sees that there is an implicit conversion from B to int, and an implicit (built-in) conversion from int to decimal, so that it can use both in sequence. In other words, the call becomes D((decimal)(int)b).
Note that nothing is being truncated; rather, an int is being promoted to a decimal. If instead you comment out the int conversion, I expect that I(b) will fail, since even though there is an implicit cast from B to decimal, there is no implicit cast from decimal to int.
when you comment that line out it takes the int operator because there is an implicit conversion of int to decimal...
I want some idea to how implicitly convert nullable "?" variables to district ones.
given this example
int? x = 5;
int y = x; //this gonna fail, !!!
i need some way to override = parameter, but unfortunately the = parameter is not overloadable... any suggestions
I'm using C#
You have two options, access the value directly (if you know for sure it's not null):
int y = x.Value;
or, use the null coalescing operator:
int y = x ?? 0; // 0 if null...
It is possible to implement an implicit cast operator, but only to or from types you define. For example, doing something like this..
public class NullableExtensions
{
public static implicit operator int(int? value)
{
return value ?? default(int);
}
}
.. will return a CS0556 compile error because the cast doesn't include the user-defined type.
The closest you could do is define your own Nullable type that does contain an implicit cast operator:
public struct ImplicitNullable<T> where T: struct
{
public bool HasValue { get { return this._value.HasValue; } }
public T Value { get { return this._value.Value; } }
public ImplicitNullable(T value) : this() { this._value = value; }
public ImplicitNullable(Nullable<T> value) : this() { this._value = value; }
public static implicit operator ImplicitNullable<T>(T value) { return new ImplicitNullable<T>(value); }
public static implicit operator ImplicitNullable<T>(Nullable<T> value) { return new ImplicitNullable<T>(value); }
public static implicit operator T(ImplicitNullable<T> value) { return value._value ?? default(T); }
public static implicit operator Nullable<T>(ImplicitNullable<T> value) { return value._value; }
private Nullable<T> _value { get; set; }
// Should define other Nullable<T> members, especially
// Equals and GetHashCode to avoid boxing
}
Note that although it's possible to write this code, it will likely lead to hard to trace bugs. I would recommend using an explicit cast, or throwing an exception when the value is null.
Afterwards, you can cast to and from as expected:
static void Main()
{
int myInt = 1;
int? nullableInt = 2;
ImplicitNullable<int> implicitInt;
// Convert from int or int?
implicitInt = myInt;
implicitInt = nullableInt;
// Convert to int or int?
myInt = implicitInt;
nullableInt = implicitInt;
}
Wait, I'm so confused...
Why don't you just use GetValueOrDefault?
I'm assuming this is C#.
You need to either cast, or use .value:
int? x = 5;
int y;
if(x.HasValue)
y = x.Value;
else
throw new//... handle error or something
Can I overload operators for class A in class B in C#? For example:
class A
{
}
class B
{
public static A operator+(A x, A y)
{
...
}
}
No; one of the parameters must be the containing type.
From section §10.10.2 of the language specification (version 4.0):
The following rules apply to binary operator declarations, where T denotes the instance type of the class or struct that contains the operator declaration:
• A binary non-shift operator must take two parameters, at least one of which must have type T or T?, and can return any type.
You should think about why. Here's one reason.
class A { }
class B { public static A operator+(A first, A second) { // ... } }
class C { public static A operator+(A first, A second) { // ... } }
A first;
A second;
A result = first + second; // which + ???
Here's another:
class A { public static int operator+(int first, int second) { // ... } }
Assume this allowed for a moment.
int first = 17;
int second = 42;
int result = first + second;
Per the specification for operator overload resolution (§7.3.2), A.+ will have precedence over Int32.+. We've just redefined addition for ints! Nasty.
No, you can't. error CS0563: One of the parameters of a binary operator must be the containing type
"In each case, one parameter must be the same type as the class or struct that declares the operator" quote from
Documentation on overloading operators.
Generally saying NO, but you can do something like following, if it helps :)
class A
{
public static A operator +(A x, A y)
{
A a = new A();
Console.WriteLine("A+"); // say A
return a;
}
}
class B
{
public static A operator +(A x, B y)
{
A a = new A();
Console.WriteLine("return in:A,B in out:A in class B+"); // say B
return a;
}
public static A operator +(B x, B y)
{
A a = new A();
Console.WriteLine("return in:B,B in out:A in class B +");
return a;
}
// and so on....
}
B b = new B();
A a = new A();
A a1 = new A();
B b1 = new B();
a = b + b1; // here you call operator of B, but return A
a = a + a1; // here you call operator of A and return A
To understand your problem, can i ask why you want to do that? :)