Zufall - Math

rand
Generates a pseudorandom number.
int rand( void );

Routine	Required Header	Compatibility
rand	<stdlib.h>	ANSI, Win 95, Win NT

Remarks
The rand function returns a pseudorandom integer in the range 0 to RAND_MAX.
Use the srand function to seed the pseudorandom-number generator before calling rand.

Subject: Floating-Point Support Routines
Keywords: See also srand

Return Value

rand	returns a pseudorandom number, as described above. There is no error return.

Example
/* RAND.C: This program seeds the random-number generator
* with the time, then displays 10 random integers.
*/

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

void main( void )
{
int i,ir;
float rmax,fr;

/* Get pseudo-random range */
rmax = float(RAND_MAX);

/* Seed the random-number generator with current time so that
* the numbers will be different every time we run.
*/
srand( (unsigned)time( NULL ) );

/* Display 10 numbers. */
for( i = 0; i < 10;i++ )
ir = rand();
fr = float(ir)/rmax;
printf( " %6d %6f\n", ir,fr);
}

Output
6929 0.001251
8026 0.563585
21987 0.193304
30734 0.808740
20587 0.585009
6699 0.479873
22034 0.350291
25051 0.895962
7988 0.822840
10104 0.746605

srand
Sets a random starting point.
void srand( unsigned int seed );

Routine	Required Header	Compatibility
srand	<stdlib.h>	ANSI, Win 95, Win NT

Remarks
The srand function sets the starting point for generating a series of pseudorandom integers. To reinitialize the generator, use 1 as the seed argument. Any other value for seed sets the generator to a random starting point. rand retrieves the pseudorandom numbers that are generated. Calling rand before any call to srand generates the same sequence as calling srand with seed passed as 1.

Subject: Floating-Point Support Routine
Keywords: See also rand

Return Value
None

Parameter

seed	Seed for random-number generation

Example
/* RAND.C: This program seeds the random-number generator
* with the time, then displays 10 random integers.
*/

#include <stdlib.h>
#include <stdio.h>
#include <time.h>

Math and related	Random Numbers
rand	Generate a pseudorandom number.
srand	Set a random starting point.

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