Rounding down a decimal value [vs 2005]

[Devdude]

Hi,

Does anyone know how to round down a decimal value?

example:

decValue1 = 1.22

I would like to have this rounded to 1




THanks,

[Lectere]

Math.Ceiling

[Lectere]

Sorry thats not it... this returns 2

[talkro]

then math.floor

[Lectere]

Dim a As Double = 1.22
MsgBox(Math.Round(a))

this is it!, good luck, thanks for the status points!

math.round

Don't forget to mark this post as resolveld!

[dbasnett]

math.floor

[dbasnett]

Dim a As Double = 1.22
MsgBox(Math.Round(a))

this is it!, good luck, thanks you for the status points!

i thought it was decimal, not double.

[Lectere]

i thought it was decimal, not double.

same result...

[dbasnett]

        Dim decNum As Decimal = 1.6D, resDecNum As Decimal
        resDecNum = Math.Ceiling(decNum)'2
        resDecNum = Math.Floor(decNum)'1
        resDecNum = Math.Round(decNum)'2
        decNum = 1.4D
        resDecNum = Math.Ceiling(decNum)'2
        resDecNum = Math.Floor(decNum)'1
        resDecNum = Math.Round(decNum)'1
        decNum = 1.5D
        resDecNum = Math.Ceiling(decNum)'2
        resDecNum = Math.Floor(decNum)'1
        resDecNum = Math.Round(decNum)'2

[dbasnett]

same result...

I don't know what the OP had in mind, but if they meant Decimal, then that is what I did.

It seems that a lot of people think these are the same, but they are not.

Dim x as Decimal = 1.22D
Dim x as Double = 1.22 'or single

Unless you have a need for Floating Point numbers I would avoid them, especially for (see signature).

[Devdude]

Thanks for all your replies!

What I am trying to establish is the following:

I have two integer values ...

lets say: i have the following calculation

newvalue = value1 / value 2


value1 = 24
value2 = 2459

What datatype should newvalue be?

I had the opinion that it should be a decimal.

Further to that ... I would like to round this number down ... as I am using it to select a case using that newvalue index, which is used to assess the progress of my process.

I am just trying out the math.floor function

Thanks

[Devdude]

Math.Floor works just fine for my decimal variable.


Thanks all ...

[dbasnett]

The selection of Data Type should meet the requirements. If you are calculating orbits use double, change from a dollar use decimal, counting from 1 to 100 use integer, etc.

Most of the time, you won't see a difference, but at least in one instance on this forum, I saw decimal v. double make a difference.

Another piece of advice:
Option Strict On
should be line 1 of your code.

[stanav]

Another piece of advice:
Option Strict On
should be line 1 of your code.

I totally agree with you on this. Everyone should turn option strict on in VS Options to make it the default for all projects. Only turn it off manually for the class/module that requires the use of late binding.

[Jenner]

Ditto. Option Strict On should be a law for posting code to these forums. When strict conversion is followed, it solves SO many issues, it's not even funny.

[03myersd]

I know this is legacy code (but its early in the morning and I haven't got my .NET head on) but it its rounding down every time to the nearest integer then why can't you use:

var = Int(var)

Seems pretty easy?

[dbasnett]

Not what I expected.

        Dim decN As Decimal = -1.6D, nuDecN As Decimal

        For x As Integer = 1 To 33
            Debug.Write("Number " & decN.ToString)
            nuDecN = Int(decN)
            Debug.Write("   <Int " & nuDecN.ToString)
            nuDecN = Math.Floor(decN)
            Debug.Write(">  <Floor " & nuDecN.ToString)
            nuDecN = Math.Ceiling(decN)
            Debug.Write(">  <Ceil " & nuDecN.ToString)
            nuDecN = Math.Round(decN)
            Debug.Write(">  <Round " & nuDecN.ToString)
            'http://msdn.microsoft.com/en-us/library/k7ycc7xh.aspx
            If decN < 0 Then
                nuDecN = Math.Ceiling(decN)
            Else
                nuDecN = Math.Floor(decN)
            End If
            Debug.WriteLine(">  <Choice " & nuDecN.ToString & ">")
            decN += 0.1D
        Next
        Stop

Number -1.6 <Int -2> <Floor -2> <Ceil -1> <Round -2> <Choice -1>
Number -1.5 <Int -2> <Floor -2> <Ceil -1> <Round -2> <Choice -1>
Number -1.4 <Int -2> <Floor -2> <Ceil -1> <Round -1> <Choice -1>
Number -1.3 <Int -2> <Floor -2> <Ceil -1> <Round -1> <Choice -1>
Number -1.2 <Int -2> <Floor -2> <Ceil -1> <Round -1> <Choice -1>
Number -1.1 <Int -2> <Floor -2> <Ceil -1> <Round -1> <Choice -1>
Number -1.0 <Int -1> <Floor -1> <Ceil -1> <Round -1> <Choice -1>
Number -0.9 <Int -1> <Floor -1> <Ceil 0> <Round -1> <Choice 0>
Number -0.8 <Int -1> <Floor -1> <Ceil 0> <Round -1> <Choice 0>
Number -0.7 <Int -1> <Floor -1> <Ceil 0> <Round -1> <Choice 0>
Number -0.6 <Int -1> <Floor -1> <Ceil 0> <Round -1> <Choice 0>
Number -0.5 <Int -1> <Floor -1> <Ceil 0> <Round 0> <Choice 0>
Number -0.4 <Int -1> <Floor -1> <Ceil 0> <Round 0> <Choice 0>
Number -0.3 <Int -1> <Floor -1> <Ceil 0> <Round 0> <Choice 0>
Number -0.2 <Int -1> <Floor -1> <Ceil 0> <Round 0> <Choice 0>
Number -0.1 <Int -1> <Floor -1> <Ceil 0> <Round 0> <Choice 0>
Number 0.0 <Int 0> <Floor 0> <Ceil 0> <Round 0> <Choice 0>
Number 0.1 <Int 0> <Floor 0> <Ceil 1> <Round 0> <Choice 0>
Number 0.2 <Int 0> <Floor 0> <Ceil 1> <Round 0> <Choice 0>
Number 0.3 <Int 0> <Floor 0> <Ceil 1> <Round 0> <Choice 0>
Number 0.4 <Int 0> <Floor 0> <Ceil 1> <Round 0> <Choice 0>
Number 0.5 <Int 0> <Floor 0> <Ceil 1> <Round 0> <Choice 0>
Number 0.6 <Int 0> <Floor 0> <Ceil 1> <Round 1> <Choice 0>
Number 0.7 <Int 0> <Floor 0> <Ceil 1> <Round 1> <Choice 0>
Number 0.8 <Int 0> <Floor 0> <Ceil 1> <Round 1> <Choice 0>
Number 0.9 <Int 0> <Floor 0> <Ceil 1> <Round 1> <Choice 0>
Number 1.0 <Int 1> <Floor 1> <Ceil 1> <Round 1> <Choice 1>
Number 1.1 <Int 1> <Floor 1> <Ceil 2> <Round 1> <Choice 1>
Number 1.2 <Int 1> <Floor 1> <Ceil 2> <Round 1> <Choice 1>
Number 1.3 <Int 1> <Floor 1> <Ceil 2> <Round 1> <Choice 1>
Number 1.4 <Int 1> <Floor 1> <Ceil 2> <Round 1> <Choice 1>
Number 1.5 <Int 1> <Floor 1> <Ceil 2> <Round 2> <Choice 1>
Number 1.6 <Int 1> <Floor 1> <Ceil 2> <Round 2> <Choice 1>

[jmcilhinney]

Thanks for all your replies!

What I am trying to establish is the following:

I have two integer values ...

lets say: i have the following calculation

newvalue = value1 / value 2


value1 = 24
value2 = 2459

What datatype should newvalue be?

I had the opinion that it should be a decimal.

Further to that ... I would like to round this number down ... as I am using it to select a case using that newvalue index, which is used to assess the progress of my process.

I am just trying out the math.floor function

Thanks

See, this is why it is important to provide a clear and full description of the issue in the first place. If you'd posted this at the start then all this could have been avoided. Division of Integers will ALWAYS return a Double. That's how the division operator is defined for the Integer type. What you should be doing is using integer division:

'Note the backslash.
Dim quotient As Integer = dividend \ divisor

Integer division will always return an Integer containing only the whole part of the result of a division. Note that Integer division differs from Math.Ceiling and Math.Floor in that it rounds toward zero, while Math.Floor rounds toward -ve infinity and Math.Ceiling will round toward +ve infinity. The code above is equivalent to this:

Dim result As Double = dividend / divisor
Dim quotient As Integer
 
If result >= 0 Then
    'Round down toward zero.
    quotient = CInt(Math.Floor(result))
Else
    'Round up toward zero.
    quotient = CInt(Math.Ceiling(result))
End If

Which is also equivalent to this:

Dim quotient As Integer = CInt(Math.Truncate(dividend / divisor))