#include<stdio.h>
#include<math.h>
int?isPrime(int?n)
{
	int?i;
	for(i=2;i<=sqrt(n);i++)
	{
		if(n%i==0)
			return?0;
	}
	if(n==1)
		return?0;
	return?1;
}
void?main()?
{?
	int?i,j,t,count=0;
	int?a,b,flag;
	printf("請輸入兩個正整數:");
	scanf("%d%d",&a,&b);
	if(a>b)
	{
		t=a;
		a=b;
		b=t;
	}
	printf("[%d,%d]的素數有:\n",a,b);
	for(i=a;i<=b;i++)
	{
		if(isPrime(i))
		{
			printf("%5d",i);
			count++;
		}
		if(count%5==0)
		{
			printf("\n");
		}
	}
	printf("\n");
}

#include<stdio.h>
#include<math.h>
void?main()?
{?
	int?i,j,t,count=0;
	int?a,b,flag;
	printf("請輸入兩個正整數:");
	scanf("%d%d",&a,&b);
	if(a>b)
	{
		t=a;
		a=b;
		b=t;
	}
	printf("[%d,%d]的素數有:\n",a,b);
	for(i=a;i<=b;i++)
	{
		flag=1;
		for(j=2;j<=sqrt(i);j++)
		{
			if(i%j==0)
				flag=0;
		}
		if(i==1)
			flag=0;
		if(flag)
		{
			printf("%5d",i);
			count++;
		}
		if(count%5==0)
		{
			printf("\n");
		}
	}
	printf("\n");
}