Rnd

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Rnd

Returns a random Double from 0 up to but not including 1.

Syntax

Declare Function Rnd ( ByVal seed As Single = 1.0 ) As Double

Parameters

• seed
• seed

Description

Returns a number of type Double in the range [0, 1) (i.e. 0 <= Rnd < 1), based on a random seed (see Randomize).

Rnd can use a variety of different algorithms - see Randomize for details of the default and selectable algorithms.

Rnd will return the same sequence of numbers every time a program is run. This sequence can be changed by reseeding the generator.

Note:

Rnd is thread-safe (by using an internal mutex), but not thread specific. Used in the context of a multi-threaded program, only the execution speed is significantly slowed down compared to a single thread call context.
Unfinished structures for other random number generators are also available in the standard header "fbprng.bi".

Return Value

Returns the random number generated.

Remarks

Usage

result = Rnd( seed )

Dialect Differences

The default algorithm used depends on the current dialect in use:

Differences from QB

• None, if compiled in the -lang qb dialect. Other dialects can also use the same seeding and generating algorithms by calling Randomize with the appropriate parameter. For the non-QB-compatible algorithms, if the optional argument is less than 0, it has the same meaning as passing an argument of 1.

See also

• Randomize
• Timer
• Int

Examples

'' Function to a random number in the range [first, last), or {first <= x < last}.

Function rnd_range (first As Double, last As Double) As Double

    Function = Rnd * (last - first) + first

End Function

'' seed the random number generator, so the sequence is not the same each time

Randomize

'' prints a random number in the range [0, 1), or {0 <= x < 1}.

Print Rnd

'' prints a random number in the range [0, 10), or  {0 <= x < 10}.

Print Rnd * 10

'' prints a random integral number in the range  [1, 10], or {1 <= n <= 10}.

''     (because: 0 <= Rnd * 10 < 10)

Print Int(Rnd * 10) + 1

'' prints a random integral number in the range [69, 420], or {69 <= n <= 420}.

''     (because: 69 <= rnd_range(69, 421) < 421)

Print Int(rnd_range(69, 421))

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Category: Mathematical Functions
Kind: function

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.