C#•2mo ago

Number With Decimal Point

how to make a number with a decimal point?

43 Replies

I have a question because there are 3 different decimal points: float, double, and decimal Which one is the best to encode a number with 3 digits before the decimal point and 2 digits after the decimal point any number between 100.01 and 999.99 with exactly 3 digits before the decimal point and exactly 2 digits after the decimal point

Pope•2mo ago

not one is best. They all have different purposes.

Pszczółka ErinaOP•2mo ago

i want the number? which one will give the correct precision?

Pope•2mo ago

float gives about 6 decimal places, double 10, decimal 15

Pszczółka ErinaOP•2mo ago

so that 999.99 won't suddenly turn into 1000

Cattywampus•2mo ago

based on the example you want decimal likely

cathei•2mo ago

Integer

Pope•2mo ago

float is fine with 999.99

Pszczółka ErinaOP•2mo ago

is float fine with 999.99 + 0.01 = 1000?

MODiX•2mo ago

Pope

REPL Result: Success

var x = 999.99f;
for (var i = 0; i < 10_000; i++)
{
    x += 0.00001f;
}
Console.WriteLine(x);

var x = 999.99f;
for (var i = 0; i < 10_000; i++)
{
    x += 0.00001f;
}
Console.WriteLine(x);

Console Output

999.99

999.99

Compile: 442.415ms | Execution: 47.578ms | React with ❌ to remove this embed.

MODiX•2mo ago

Cattywampus

REPL Result: Success

Console.WriteLine(999.99f + 0.01f);

Console.WriteLine(999.99f + 0.01f);

Console Output

Compile: 387.629ms | Execution: 25.851ms | React with ❌ to remove this embed.

cathei•2mo ago

You should state the purpose of this number

Pope•2mo ago

It really depends on what you're planning on doing with them.

Pszczółka ErinaOP•2mo ago

for counting stuff like money, or amount of something...

Pope•2mo ago

If it's money, use decimal.

Cattywampus•2mo ago

Pope•2mo ago

If it's quantity, maybe double is fine.

Pszczółka ErinaOP•2mo ago

but it's for a temporary mantissa without exponent and then the main money would be decimal

Pope•2mo ago

If you're going to be doing exponentiation with it, double might be the best.

Pszczółka ErinaOP•2mo ago

is float ok for the mantissa or is it double?

Pope•2mo ago

if it's for money, just use long cents.

Muhammad Ali•2mo ago

I never used float but decimal provides you more precise value in c# by using celing and floor software based functions. but double use binary operations and provide you accurate value in most efficient way.

cathei•2mo ago

decimal type is pretty much for money

Pope•2mo ago

decimal type is denoted by m, which stands for money

Cattywampus•2mo ago

fucking Pope typing super quick

Pszczółka ErinaOP•2mo ago

I know but I want like a int 12345 (mantissa) turn into 123.45 times 1000^n how to store 123.45

Sehra•2mo ago

or using d would be confusing with double, so m it was

Pope•2mo ago

it's not or. It is the way it is just how I said. the etymology isn't of issue here.

Pszczółka ErinaOP•2mo ago

as a temporary variable in a method

Muhammad Ali•2mo ago

you have to use Math library functions Floor or Ceil for this purpose

cathei•2mo ago

Why do you do this

Muhammad Ali•2mo ago

No datatype will handle this.

Pszczółka ErinaOP•2mo ago

why

Pope•2mo ago

It's kind of funny that you use the word mantissa, but don't think about log10 or similar.

cathei•2mo ago

Decimal is fine. But why not either just have decimal or handle as integer :catthinking:

Pope•2mo ago

Usually I only use the word mantissa when talking about the fractional part of an exponent.

Muhammad Ali•2mo ago

datatypes are like containers to put a value. It based on you what you put inside. It is not data types duty to perform logic on your value.

Pope•2mo ago

and guess what double does under the hood for you anyways

MODiX•2mo ago

Cattywampus

REPL Result: Success

public static double ToFloatingPoint(int value)
    {
        string a = value.ToString();
        
        if (a.Length < 2)
        {
            return value;
        }

        string ab = a.Insert(a.Length - 2, ".");
        int exponent = a.Length - 2 -3;
        double baseNumber = double.Parse(ab);
        double result = baseNumber * Math.Pow(1000, exponent);
        return baseNumber;
    }
        double result = ToFloatingPoint(12345);
        Console.WriteLine(result);

public static double ToFloatingPoint(int value)
    {
        string a = value.ToString();
        
        if (a.Length < 2)
        {
            return value;
        }

        string ab = a.Insert(a.Length - 2, ".");
        int exponent = a.Length - 2 -3;
        double baseNumber = double.Parse(ab);
        double result = baseNumber * Math.Pow(1000, exponent);
        return baseNumber;
    }
        double result = ToFloatingPoint(12345);
        Console.WriteLine(result);

Console Output

123.45

123.45

Compile: 455.555ms | Execution: 50.875ms | React with ❌ to remove this embed.

Cattywampus•2mo ago

you don't? you generally don't want to round for money or else, well.. you'll lose money 🙂

Muhammad Ali•2mo ago

ummm. but he wants to round it to 2 digits only...

Cattywampus•2mo ago

truncation or rounding? those are two different things

Muhammad Ali•2mo ago

I never read about truncation. So, I don't know about it. Let me check what it is.

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