pe 7-9 比输入数小的所有素数.txt

c primer 部分习题答案

#include <stdio.h>
#define NO 0
#define YES 1
int main(void)
{
   long num,div,lim;                    
   int prime;
 
   printf("Please enter limit to values to be checked; ");
   printf("Enter q to quit.\n");
   while (scanf("%ld", &lim) == 1 && lim > 0)
   {
         for (num = 2; num <= lim; num++)
         {               
          for (div = 2, prime = YES; (div * div) <= num; div++)
             if (num % div == 0)
                prime = NO;          
          if (prime == YES)
             printf("%ld is prime.\n", num);
      }
      printf("Please enter another limit; ");
      printf("Enter q to quit.\n");
   }
   return 0;
}