How to Determine the Variable Type

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

When using the Visual FoxPro TYPE() function, you must ensure that the expression passed to the function is always be of the character type. You can use a user-defined function (UDF) to determine the type of a variable without trying to convert the variable to a character string. This article shows you how to do it.

MORE INFORMATION

Step-by-Step Example

1. Open a program file, and type the following function into it:

   FUNCTION ALLTYPE

       *
       *  Purpose:  Determine the data type of a variable
       *  Syntax:   m.cNewValue = ALLTYPE(<Variable Name>)
       *  Parms:    xxx (Can be Character, Numeric, Date, or Logical)
       *            The variable for which the type is to be determined.
       *  Return:   lcType:  C for Character
       *                     N for Numeric
       *                     D for Date
       *                     L for Logical
       *  Example:  lcTheType=ALLTYPE(Variable)
       *
       PARAMETER xxx
       local llType,lcType
       lcTemperror=ON('ERROR')
       ON ERROR llType=.f.
       llType=.T.
       xxx=xxx+" "
       IF llType
         lcType="C"
       ENDIF
       llType=.T.
       xxx=!xxx
       IF llType
         lcType="L"
       ENDIF
       llType=.T.
       xxx=xxx+1
       IF llType
         lcType="N"
       ENDIF
       llType=.T.
       xxx=MONTH(xxx)
       IF llType
         lcType="D"
       ENDIF
       ON ERROR &lcTemperror
      RETURN lcType
   
   

2. Save and close the program file.

3. In the Command window, type the following:

   SET PROCEDURE TO <Program File> x=3 ? ALLTYPE(x)

4. The value returned is N.

   ? TYPE('x')