从键盘输入一个整数，输出距离该数最近的素数 

#include
    
     #include
     
      int judge(int x) {			//判断素数	if (x < 2)		return 0;	for (int i = 2; i <= sqrt(x); i++)		if (x % i == 0)			return 0;	return 1;}int main() {	int s, left, right, flag = 0;	int count = 0;		//记录个数	int result[2];		//记录结果	printf("Input num:");	scanf("%d", &s);	left = right = s;	while (flag == 0) {		if (left>0&&judge(--left)) {		//左边小于0时就不用再判断素数了			result[count++] = left;			flag = 1;		}		if (judge(++right)) {			result[count++] = right;			flag = 1;		}	}	if (count == 1)		printf("Prime number is %d", result[0]);	else		printf("Prime number are %d,%d", result[0], result[1]);	return 0;}