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コード: 全て選択

Function RoundDown (dbl As Double, Keta As Long, Mode As Long) As Double
	If dbl = Int(dbl) Then
		RoundDown = dbl
		Exit Function
	End If
	dbl = dbl*10^Keta
	Select Case Mode
		Case 1'切り捨て
			dbl = Int(dbl)
		Case 2'切り上げ
			If dbl - Int(dbl) >= 0.1 Then
				dbl = Int(dbl+1)
			Else
				dbl = Int(dbl)
			End If
		Case 3'四捨五入
			If dbl - Int(dbl) >= 0.5 Then
				dbl = Int(dbl+1)
			Else
				dbl = Int(dbl)
			End If
		Case 4'五捨六入
			If dbl - Int(dbl) >= 0.6 Then
				dbl = Int(dbl+1)
			Else
				dbl = Int(dbl)
			End If
		Case 5'JIS丸め
			If dbl - Int(dbl) > 0.5 Then
				dbl = Int(dbl+1)
			ElseIf dbl - Int(dbl) < 0.5 Then
				dbl = Int(dbl)
			Else
				If Int(dbl) mod 2 Then
					dbl = Int(dbl+1)
				Else
					dbl = Int(dbl)
				End If
			End If
	End Select
	dbl /= 10^Keta
	RoundDown = dbl
End Function

コード: 全て選択

#prompt
Dim A As Double
Print "元値","切捨","切上","四五","五六","JIS"
A=8.05
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.15
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.25
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.26
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.34
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.35
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)
A=8.45
Print A,RoundDown(A, 1, 1),RoundDown(A, 1, 2),RoundDown(A, 1, 3),RoundDown(A, 1, 4),RoundDown(A, 1, 5)

コード: 全て選択

#prompt
Dim A As Double
A=0.0000000000000005
Print A

コード: 全て選択

Function GetNumberFormatDecimal(ByVal lpValue As BytePtr,ByVal nDecimals As Long) As BytePtr
Dim length As Long, cnt As Long

	' コンマの位置を取得
	While lpValue[cnt]<>Asc(".")
		cnt++
	Wend

	' コンマまでの文字数と小数点以下の桁数とコンマ自身の 1
	length=cnt+nDecimals+1
	GetNumberFormatDecimal=calloc(length+1)
	memcpy(GetNumberFormatDecimal,lpValue,length)
End Function

' 使い方
Dim str As BytePtr
	str=GetNumberFormatDecimal(Str$(100.123456789),5)

	' 100.12345 と表示されます
	MessageBox(hMainWnd,str,"",MB_OK)

	free(str)

コード: 全て選択

Function Str2$(dbl As Double,sKeta As Long) As String'第二引数は、小数点以下何桁まで表示するかを選びます。あまり数がおおくなると誤差が大きくなります。
	Dim A$ As String
	Dim B$ As String
	Dim I As Long
	A$=Str$(Int(dbl))
	dbl=dbl-Int(dbl)
	If sKeta<=0 then
		Str2$=A$
	Else
		B$="."
		I=1
		Do
			dbl=dbl*10
			B$=B$+Str$(Int(dbl))
			dbl=dbl-Int(dbl)
			If I>=sKeta then Exit Do
			I=I+1
		Loop
		Str2$=A$+B$
	End If
End Function


Function Str3$(dbl As Double,sKeta As Long) As String'第二引数は、小数点以下何桁まで表示するかを選びます。あまり数がおおくなると誤差が大きくなります。
	Dim A$ As String
	Dim I As Long
	A$=Str$(dbl)
	I=InStr(1,A$,".")
	If I=0 then
		Str3$=A$
	Else
		For I=1 To 100
			A$=A$+"0"
		Next I
		Str3$=Mid$(A$,1,InStr(1,A$,".")+sKeta)
	End If
End Function