How To Determine Whether a Number is Prime

ID: Q153200

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b
Microsoft FoxPro for Macintosh, versions 2.5b, 2.5c, 2.6a
Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, 2.5a, 2.5b, 2.6, 2.6a
Microsoft FoxPro for UNIX, version 2.6
Microsoft Visual FoxPro for Macintosh, Professional Edition, version 3.0

SUMMARY

There is no single function in FoxPro or Visual FoxPro that determines whether a number is prime. This article describes how to use a program that allows you to enter a positive number and then reports if that number is prime.

MORE INFORMATION

A prime number is a number divisible only by one and itself. The following program uses the MOD()and ABS() functions along with a For...Next loop to check if a number is prime:


   CLEAR
   SET TALK OFF
   x=0
   @ 1,10 SAY "Please enter a positive integer"  GET x
   READ
   x=ABS(x)
   FOR i=2 to x-1
      IF MOD(x,i)=0
          @2,10 SAY  "The number "+ ALLTRIM(STR(x))+ " is not prime."
          RETURN
      ENDIF
   ENDFOR
   @ 2,10 SAY "The number "+ ALLTRIM(STR(x))+ " is prime."
   SET TALK ON

While this program uses the READ statement for backward compatibility with FoxPro 2.x versions, the basic algorithm may be used in a form within Visual FoxPro.

Additional query words: VFoxWin VFoxMac

Keywords : FxprgGeneral
Version : MACINTOSH:2.5b,2.5c,2.6a; MS-DOS:2.0,2.5,2.5a,2.5b,2.6,2.6a; UNIX:2.6; WINDOWS:3.0,3.0b; :3.0
Platform : MACINTOSH MS-DOS UNIX WINDOWS
Issue type :