How to Create an Array of Unique Random Numbers (136420)

MORE INFORMATION

Step-by-Step Example

1. Create a program file called Myudf.prg that contains the following code:

      FUNCTION RANDOM
      *  Returns a random number between any 2 numbers.
      *  Syntax: =RANDOM(Lower Value, Higher Value)
      *  Example:  lnX=RANDOM(5,10)
      PARAMETER anLow,anHigh
      lnRnumber=INT((RAND()*(anHigh-anLow+1))+anLow)
      RETURN lnRnumber
   
      FUNCTION A_RANDOM
      *  Returns an array of random numbers between any 2 numbers.
      *  The array must already be defined
      *  Syntax:   =A_RANDOM(ArrayName,Lower Value, Upper Value)
      *  Example:  =A_RANDOM('gaMyarray',17,25)
      PARAMETER lcA_name,anLow,anHigh
      lnAlength=ALEN(&lcA_name)
      FOR lni=1 TO lnAlength
        &lcA_name(lni)=INT((RAND()*(anHigh-anLow+1))+anLow)
      ENDFOR
      RETURN &lcA_name
   
      FUNCTION U_RANDOM
      *  Returns an array of unique random numbers  between any 2 numbers.
      *  The array must already be defined
      *  Syntax:   =U_RANDOM(Array Name, Lower Value, Upper Value)
      *  Example:  =U_RANDOM('gaMyarray',1,10)
      PARAMETER lcA_name,anLow,anHigh
      lnAlength=ALEN(&lcA_name)
      IF lnAlength>anHigh-anLow
         lnAlength=anHigh-anLow+1
      ENDIF
      &lcA_name=.F.
      lni=1
      DO WHILE lni<=lnAlength
         lnRnumber=INT((RAND()*(anHigh-anLow+1))+anLow)
         llNextnum=.T.
         IF lnRnumber=anLow .OR. lnRnumber=anHigh
            DO CASE
            CASE lnRnumber=anLow
               lnK=1
               DO WHILE lnK>0
                  anLow=anLow+1
                  lnK=ASCAN(&lcA_name,anLow)
               ENDDO
            CASE lnRnumber=anHigh
               lnK=1
               DO WHILE lnK>0
                  anHigh=anHigh-1
                  lnK=ASCAN(&lcA_name,anHigh)
               ENDDO
            ENDCASE
         ELSE
            lnK=ASCAN(&lcA_name,lnRnumber)
            IF lnK>0
               llNextnum=.F.
            ENDIF
         ENDIF
         IF llNextnum
            &lcA_name(lni)=lnRnumber
            lni=lni+1
         ENDIF
      ENDDO
   						

2. Save and Close Myudf.prg
3. Test the functions:
   
   
   1. To print a single random number between 5 and 10, type the following in the Command window:

            SET PROCEDURE TO MYUDF.PRG
            ? RANDOM(5,10)
      								

   2. To populate an array with random numbers, type the following in the Command window:

            SET PROCEDURE TO MYUDF.PRG
            DIMENSION gaMyarray(10)
            =A_RANDOM('gaMyarray',1,10)
      								

   3. If you want to populate an array with unique random numbers, type the following in the Command window:

            SET PROCEDURE TO MYUDF.PRG
            DIMENSION gaMyarray(10)
            U_Random('gaMyarray',1,10)