xlvba random function code example

Example 1: excel vba random

'VBA has the Rnd() function which returns a random single floating point value
'between 0 and 1, but not including 1.

MsgBox Rnd		'<--displays something like 0.74323

'To generate integer values between two integer numbers, use the following formula:
'Int((max - min + 1) * Rnd + min)

'For example, to generate random integers between 11 and 14:
MsgBox Int((14 - 11 + 1) * Rnd + 11)    '<--displays 11 or 12 or 13 or 14	

'------------------------------------------------------------------------------

'Note: If min is ONE for the above range to randomly select from, then 
'      the formula can be shortened to: Int(Rnd * max + 1):

MsgBox Int(Rnd * 4 + 1)		'<--randomly displays 1 or 2 or 3 or 4

'Note: If min is ZERO for the above range to randomly select from, then 
'      the formula can be shortened to: Int(Rnd * (max + 1)):

MsgBox Int(Rnd * (3 + 1))	'<--randomly displays 0 or 1 or 2 or 3

'------------------------------------------------------------------------------

'Note: Each time the Rnd() function is called a different random single floating 
'      point value will be returned. But Rnd() is likely to produce 
'      the same SEQUENCE of random values if the procedure containing
'      the multiple calls to the Rnd() function is accessed later.
'
'      To ensure that the routine procuces a fresh sequence of random
'      numbers when the routine is later called again, use the VBA
'      Randomize statement once:

Sub RandomSequence()
    Randomize
    Debug.Print Rnd, Rnd, Rnd
End Sub


'Reference:
    https://docs.microsoft.com/en-us/office/vba/language/reference/user-interface-help/randomize-statement

Example 2: excel vba randbetween

'VBA has the Rnd() function which returns a random single floating point value
'between 0 and 1, but not including 1.

MsgBox Rnd		'<--displays something like 0.74323

'To generate integer values between two integer numbers, use the following formula:
'Int((max - min + 1) * Rnd + min)

'For example, to generate random integers between 11 and 14:
MsgBox Int((14 - 11 + 1) * Rnd + 11)    '<--displays 11 or 12 or 13 or 14	

'------------------------------------------------------------------------------

'Note: If min is ONE for the above range to randomly select from, then 
'      the formula can be shortened to: Int(Rnd * max + 1):

MsgBox Int(Rnd * 4 + 1)		'<--randomly displays 1 or 2 or 3 or 4

'Note: If min is ZERO for the above range to randomly select from, then 
'      the formula can be shortened to: Int(Rnd * (max + 1)):

MsgBox Int(Rnd * (3 + 1))	'<--randomly displays 0 or 1 or 2 or 3

'------------------------------------------------------------------------------

'Note: Each time the Rnd() function is executed a different random single floating 
'      point value will be returned. But Rnd() is likely to produce 
'      the same SEQUENCE of random values if the procedure containing
'      the multiple calls to the Rnd() function is accessed later.
'
'      To ensure that the routine procuces a fresh sequence of random
'      numbers when the routine is later called again, use the VBA
'      Randomize statement once:

Sub RandomSequence()
    Randomize
    Debug.Print Rnd, Rnd, Rnd
End Sub


'Reference:
    https://docs.microsoft.com/en-us/office/vba/language/reference/user-interface-help/randomize-statement