HOWTO: Convert a Fraction to a Decimal Number

ID: Q185424

The information in this article applies to:

Microsoft Visual Basic for Applications version 5.0

SUMMARY

This article provides a routine to convert a string that contains a fraction in the form "a," "a/b," or "a b/c" into a double precision floating-point number.

MORE INFORMATION

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Sometimes it is more convenient to input values as fractions instead of decimal numbers. The following routine converts a string containing a fraction to a decimal number:

1. Create a new Visual Basic for Applications project and add the following

   code to a module:

   Sample Code
   -----------

      Function Frac2Num(ByVal X As String) As Double
      Dim P As Integer, N As Double, Num As Double, Den As Double
         X = Trim$(X)
         P = InStr(X, "/")
         If P = 0 Then
            N = Val(X)
         Else
            Den = Val(Mid$(X, P + 1))
            If Den = 0 Then Error 11    ' Divide by zero
            X = Trim$(Left$(X, P - 1))
            P = InStr(X, " ")
            If P = 0 Then
               Num = Val(X)
            Else
               Num = Val(Mid$(X, P + 1))
               N = Val(Left$(X, P - 1))
            End If
         End If
         If Den <> 0 Then
            N = N + Num / Den
         End If
         Frac2Num = N
      End Function

2. In the Debug/Immediate window, test:

      ? Frac2Num("5 3/4"), Frac2Num("2/8")

   Result: 5.75      0.25

Note: Numbers in the input string do not have to be whole numbers. They can contain decimal values and negative numbers.

REFERENCES

For more information about getting help with Visual Basic for Applications, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q163435
   TITLE     : VBA: Programming Resources for Visual Basic for
               Applications

Additional query words: KbVBA kbVBp kbVBp500 kbDSupport kbDSD

Keywords          :  
Issue type        : kbhowto

Last Reviewed: May 19, 1999