C素數相關

#include<stdio.h>
#include<math.h>

int isPrime(int);
//int isPrime2(int);
//void primeDecompositon(int num);

int main()
{
	int i,count;
	int range,sum;
	i=range=0;
	while(1)
	{
		printf("range:");
		scanf("%d",&range);
		count=1;
		sum=0;
		for(i=2;i<=range;i++)
			if(isPrime(i)) 
			{
				sum+=i;
				if(i>count*10)         //打印count*10 ~ (count+1)*10-1之間的數 
				{
					printf("\n");
					count++;
				}
				printf("%d ",i);
			}
	}
	return 0;
}

int isPrime(int num)
{
	int i=0;
	if(num<2) return 1;
	else
		for(i=2;i<=(int)sqrt(num);i++)
		{
			if(num%i==0) break;
		}
	if(i>(int)sqrt(num)) return 1;
	else return 0;
	
} 



/*
int main()
{
	int num=0;
	while(1)
	{
		printf("please input an integer:");
		scanf("%d",&num);
		primeDecompositon(num);
	}
	return 0;
}




int isPrime2(int num)
{
	int i=0;
	if(num<2) return 0;                  //0，1不是素數 
	else
		for(i=2;i<=(int)sqrt(num);i++)
		{
			if(num%i==0) break;
		}
	if(i>(int)sqrt(num)) return num;     //非break退出循環說明非素數，返回素數本身 
	else return i;                       //記錄break時的循環變量作爲分解因子 
	
} 

void primeDecompositon(int num)
{
	int factor=0;
	factor=isPrime2(num);
	if(factor==0) printf("%d is not prime.\n",num);
	else if(factor==num) printf("%d\n",factor);
	else if(factor<=(int)sqrt(num))
	{
		printf("%d*",factor);
		num=num/factor;
		primeDecompositon(num);
	}
}

*/