I got an error and I don't know why. I dont find the need to convert to double or am i supposed to to that? I am really confused right now
Argument 1: cannot convert from 'decimal' to 'double'
static void Main(string[] args)
{
Console.Write("speed: ");
string speed = Console.ReadLine();
Console.Write("Gammafaktor: ");
string Gammafaktor = Console.ReadLine();
{
}
var gamma1 = Convert.ToDecimal(Gammafaktor);
var speed1 = Convert.ToDecimal(speed);
if ( speed1 !=0 )
{
var calc = 1m / Convert.ToDecimal(Math.Sqrt(1 - speed1 * speed1));
Console.WriteLine(calc);
}
}
}
}
You are most likely seeing:
CS1503 Argument 1: cannot convert from 'decimal' to 'double'
on the line with the Math.Sqrt call, or (if you move the assignment out to a local):
CS0266 Cannot implicitly convert type 'decimal' to 'double'. An explicit conversion exists (are you missing a cast?)
Math.Sqrt takes a double, not a decimal, and the conversion from decimal to double is explicit, not implicit - meaning it isn't going to just do it automatically without you knowing about it; so:
var calc = 1m / Convert.ToDecimal(Math.Sqrt((double)(1 - speed1 * speed1)));
As a side note... that calculation looks very odd (and dangerous), unless speed1 is always between zero and one.
Related
This question already has answers here:
Cannot implicitly convert type 'double' to 'int'. -error
(4 answers)
Closed 9 months ago.
I am a beginner in C#. I'm currently trying to concatenate int data and using the Math square root function, but after running the program, it produces an error.
The code are as follows.
using System;
namespace NewProject
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Type any number");
int number = Convert.ToInt32(Console.ReadLine());
int square_root = Math.Sqrt(number);
Console.WriteLine("$The square root of {square_root} is " , square_root);
}
}
}
C:\Users\ajmal\Documents\Learn C#\New Project\Program.cs(13,31): error CS0266: Cannot implicitly convert type 'double' to 'int'. An explicit conversion exists (are you missing a cast?) [C:\Users\ajmal\Documents\Learn C#\New Project\N
ew Project.csproj]
The build failed. Fix the build errors and run again.
Any tips and help would be appreciated
The compiler message tells:
Cannot implicitly convert type 'double' to 'int'. An explicit conversion exists (are you missing a cast?)
It even gives you the location of the error:
New Project\Program.cs(13,31)
Line 13, position 31
If you look there, not very far you should find this line:
int square_root = Math.Sqrt(number);
If you look that the Math.Sqrt documentation, you'll see that Math.Sqrt returns a double.
Here is the signature from the documentation:
public static double Sqrt (double d);
So you try to put a double into an int (the type of your square_root variable), which is only possible with an explicit cast, hence the compiler message.
To fix this (supposing you want to keep a non integer value for the square root) simply correct the line with
double square_root = Math.Sqrt(number);
or you can even let the compiler do the work by leveraging the var keyword:
var square_root = Math.Sqrt(number);
Additional remarks:
The Math.Sqrt signature shows that a double is needed as parameter, but you pass an int. This is not a problem since the compiler can do an implicit conversion from an int to a double.
There will also be an error on the following line (without even considering the meaning of what you write).
Console.WriteLine("$The square root of {square_root} is " , square_root);
To concatenate strings, you can use several techniques, like composite formating and string interpolation. It seems you mix both synthax on this line.
See the string interpolation documentation:
an example of both methods taken from the documentaion:
string name = "Mark";
var date = DateTime.Now;
// Composite formatting:
Console.WriteLine("Hello, {0}! Today is {1}, it's {2:HH:mm} now.", name, date.DayOfWeek, date);
// String interpolation:
Console.WriteLine($"Hello, {name}! Today is {date.DayOfWeek}, it's {date:HH:mm} now.");
// Both calls produce the same output that is similar to:
// Hello, Mark! Today is Wednesday, it's 19:40 now.
This question already has answers here:
Int to string: cannot convert from 'method group' to 'string' [closed]
(3 answers)
Closed 4 years ago.
when I run this code it get error when i trying to use Sspeed
Argument 3: cannot convert from 'method group' to 'float'
I have try do .ToString()
public Rigidbody dot;
public float Speed = 1000f;
float Sspeed()
{
float Sspeed = Speed * Time.deltaTime;
return Sspeed;
}
void Start()
{
Debug.Log(Sspeed);
}
void FixedUpdate()
{
if (Input.GetKey("a"))
{
dot.AddForce(0, 0, Sspeed);
}
}
You're missing your brackets.
dot.AddForce(0, 0, Sspeed());
Debug.Log(Sspeed());
In c# you have to add brackets to call a method, even if it has no arguments.
This would work without brackets if Sspeed were a (readonly) Property.
As a side note, Sspeed doesn't look like a function name to me, but more like a class name, you should consider renaming it to something more telling, like getSpeed(), although it's not really a speed you're getting there, but more of a distance. (v = s/t <=> v*t = s)
Know I cast a byte to the code that I have commented but I still have the same error
public override bool StartPing(string ip)
{
base.Init();
try
{
this.sock.ReceiveTimeout = 5000;
this.sock.Connect(ip, 5055);
this.PingBytes[this.PingBytes.Length - 1] = this.PingId;
this.sock.Send(this.PingBytes);
//this.PingBytes[this.PingBytes.Length - 1] = (byte)this.PingId - 1;
}
catch (Exception value)
{
this.sock = null;
Console.WriteLine(value);
}
return false;
}
I'm not that good with setting the format yet so please bear with me.
The whole expression has to be casted :
(byte) (this.PingId - 1);
Otherwise PingId is casted to byte and then 1 is subtracted from it and as 1 is an int the byte is promoted back to an int.
private void buttonConvert_Click(object sender, EventArgs e)
{
//Convert number from C to F
double convertDecimal;
convertDecimal = 1.8;
textBoxF = double.Parse(textBoxC.Text) * double(convertDecimal) + 32;
^here is where I get the error
Error 1 Invalid expression term 'double'
I am pretty new to programming and but I just can't wrap my mind around trying to add, subtract, dividing, or multiplying numbers. I am trying to do a simple a simple conversion. Take the number from the Celsius textbox and convert it to Fahrenheit. I just don't understand the number part???
Thanks for your help!
double(convertDecimal) should be (double)convertDecimal
That looks like a C++ type-casting expression, which doesn't work in C#. And as convertDecimal already is of type double there's no need to cast it. Just use it directly:
textBoxF = double.Parse(textBoxC.Text) * convertDecimal + 32;
You only need to change the type of a variable (i.e. type-cast) when the variable is of a type not expected. Adding two double values is okay. Even adding a double and an int is okay because the integer is implicitly converted to a double.
Edit: You try to assign the result of the expression to a control, which will not work. You should convert the result to a string (e.g. with double.ToString), and then assign to the controls text field:
double farenheit = double.Parse(textBoxC.Text) * convertDecimal + 32;
textBoxF.Text = farenheit.ToString();
The example below compiles:
public static void Main()
{
Byte b = 255;
b += 100;
}
but this one below fails
public static void Main()
{
Byte b = 255;
b = b + 100;
}
with
Error 1 Cannot implicitly convert type 'int' to 'byte'. An explicit conversion exists (are you missing a cast?)
Does this mean that for C# += operator provides EXPLICIT conversion?
Eric Lippert answered your question at great length.
Another interesting aspect of the predefined compound operators is
that if necessary, a cast – an allegedly “explicit” conversion – is
inserted implicitly on your behalf. If you say
short s = 123;
s += 10;
then that is not analyzed as s = s + 10 because short plus int is int,
so the assignment is bad. This is actually analyzed as
s = (short)(s + 10);
so that if the result overflows a short, it is automatically cut back
down to size for you.
See also part two.