ex1_gen.c File Reference

Appfs Exercise 1: data generator. More...

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

Go to the source code of this file.

Functions
int	main (int argc, char **argv)
	Generate n random integer numbers and write them to stdout. More...

Detailed Description

Author

Thorsten Koch

Date

24Oct2014

gcc -std=c99 -O2 -o ex1_gen -static -m32 ex1_gen.c

Definition in file ex1_gen.c.

Function Documentation

int main	(	int	argc,
		char **	argv
	)

The first number is 123456789; Every 1000037 number the number is negative.

Definition at line 15 of file ex1_gen.c.

{
   const char* usage = "usage: %s count\n";

   /* Check arguments, we need a positive number
    */
   if (argc < 2 || atoi(argv[1]) < 1)
   {
      printf(usage, argv[0]);
      exit(-1);
   }
   const int r = 123456789;
   int       n = atoi(argv[1]);
   
   srand(130267);
   
   fwrite(&r, sizeof(r), 1, stdout);

   for(int i = 0; i < n; i++)
   {
      r = rand();  // bad random number generator
      
      if (0 != i && 0 == (i % 1000037))
         r *= -1;
      
      // fprintf(stderr, "%d\n", r);
      fwrite(&r, sizeof(r), 1, stdout);
   }
   return EXIT_SUCCESS;
}