VBA 產生隨機數字 (random & randomize 用法)

  (1) 用 "時" "分" "鈔" 做種 , 作為 每次 / 每組 新隨機數字根據
   seed = TimeValue("00:" & Format(Second(Time), "00") & ":" & Format(Minute(Time), "00"))
   Randomize (seed)
   Range("A1") = Int((100) * Rnd + 1)

 (2) 如 ran(0) , ran(-1) or rasn(-2) .... , 會產生和上一次一樣的隨機數字

 (3) Randomize  後面不加任何數值 , 會用電腦系統中的時間做seed


the below is FROM Microsoft WEBSITE

Rnd Function

Returns a Single containing a random number.

Syntax

Rnd[(number)]

The optional number argument is a Single or any valid numeric expression.

Return Values

IF NUMBER IS	RND GENERATES
Less than zero	The same number every time, using number as the seed.
Greater than zero	The next random number in the sequence.
Equal to zero	The most recently generated number.
Not supplied	The next random number in the sequence.

Remarks

The Rnd function returns a value less than 1 but greater than or equal to zero.

The value of number determines how Rnd generates a random number:

For any given initial seed, the same number sequence is generated because each successive call to the Rndfunction uses the previous number as a seed for the next number in the sequence.

Before calling Rnd, use the Randomize statement without an argument to initialize the random-number generator with a seed based on the system timer.

To produce random integers in a given range, use this formula:

Int((upperbound - lowerbound + 1) * Rnd + lowerbound)

      

Here, upperbound is the highest number in the range, and lowerbound is the lowest number in the range.

 NOTE    To repeat sequences of random numbers, call Rnd with a negative argument immediately before usingRandomize with a numeric argument. Using Randomize with the same value for number does not repeat the previous sequence.

Example

 NOTE   Examples that follow demonstrate the use of this function in a Visual Basic for Applications (VBA) module. For more information about working with VBA, select Developer Reference in the drop-down list next toSearch and enter one or more terms in the search box.

This example uses the Rnd function to generate a random integer value from 1 to 6.

Dim MyValue
' Generate random value between 1 and 6.
MyValue = Int((6 * ) + 1)