prime.c

自己做的常用库和实现的数据结构。public domain.

/*
  Ex4_5
  Generate prime numbers less than MAX  
  with Erastosthenes Sieve Algorithm       
*/
#define MAX 20

main()
{
  int    i,j;
  int    prime[MAX];

  for(i=2;i<MAX;i++)    /* First step */
      prime[i] = 0;

  for (i=2; i<MAX; )    /*  Second step  */
  {
   printf("\n\ni=%d prime[i]=%d\n",i, prime[i]);   /*  Third step  */

   for (j=1;i*j<MAX;j++)  {  /*  Fourth step  */
        prime[i*j] = 1;                
	printf("prime[%d]=1\t",i*j);
   }

   for (i=i+1;prime[i]==1 && i<MAX;i++);   /*  Fifth step  */
  }
}