Random

Random Obtain pseudo-random signed integer

#include <Quickdraw.h> Quickdraw

short Random( );

Random generates and returns a different pseudo-random number each time

it is called. The return value ranges from -32767 to 32767.

Returns: a signed integer; the next in a sequence of pseudo-random values,

uniformly distributed over the range -32767 to 32767.

Notes: To obtain a number within a selected range multiply the return value by

the range, divide by 65536, and add the desired minimum value. See the

Example, below.

The numbers are generated in a sequence based upon the starting, or "seed

value, which is stored in the global 32-bit variable randSeed.

The seed is initialized to 1 by InitGraf. If you start a sequence by storing

a value in randSeed, you can restart the same sequence by setting randSeed

to the same value. A more typical operation is to start the sequence with

some relatively unguessable value, such as the system time:

GetDateTime( &randSeed ); /* store 32-bit value in seed */

theRand = Random(); [TOKEN:12074] get a random number */

The Quickdraw global variable randSeed can also be used as a seed to start a

pseudo-random sequence.

Example

/* example function returns value between min and max */

#include <Quickdraw.h>

unsigned short RangedRdm( unsigned short min, unsigned short max )

/* assume that min is less than max */

{

unsigned qdRdm; /* treat return value as 0-65536 */

long range, t;

qdRdm = Random();

range = max - min;

t = (qdRdm * range) / 65536; /* now 0 <= t <= range */

return( t+min );

}

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