Cannot assign value of quotient when declaring a double

I'm trying to declare a double in C# that has the value of a quotient. It doesn't seem to work...

double convert = 5 / 1024;


This keeps assigning the value 0 to the variable 'convert' instead of 0.0048828125.

I am using it in a serial read to convert the 10-bit integer back to a voltage...

static void Main(string args)
{
double rawValue;
double convert = 5 / 1024; // Assigns value of 0
double convValue;
string read;

SerialPort sp = new SerialPort("COM3"); // Creates COM port
sp.BaudRate = 9600;
sp.Open();

for (;;)
{
read = sp.ReadLine();
rawValue = Convert.ToDouble(read);
convValue = rawValue * convert;
Console.WriteLine(Math.Round(convValue, 2));
}
}


The serial read works fine; I can read and write to the console the 0-1023 number and then converter it manually. I just can't assign the conversion double with the expression "5 / 1024".

Possible duplicate of Why does integer division in C# return an integer and not a float?
– Camilo Terevinto
Jun 29 at 21:53

2 Answers
2

That (5 / 1024) is integer division. In integer division: the answer is zero. To tell it to use floating point: add a decimal point:

5 / 1024

double convert = 5.0 / 1024;


Note it can also probably be declared const.

const

Try inserting a "D" after the number, this way, the compiler can identify, with clarity, the desired type (in this case, the literal "D" represents the double type, just like "M" represents decimals).

Example:
double convert = 5d / 1024d;

double convert = 5d / 1024d;

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