判断一个数是否素数.c

Explanation:
Also known prime number prime number.A natural number greater than 1, except for 1 and its own, no other natural number can be evenly divisible by the number is prime.

//  date:2020/3/4
//  author:xiezhg5
#include <stdio.h>
int main(void)
{
	int sushu(int);             //函数名(数据类型)有返回值 
	int n;
	printf("请输入一个整数:\n");
	scanf("%d",&n);
	//if-else选择结构 
	if(sushu(n))
	{
		printf("%d 是素数\n",n);
	}
	else
	{
		printf("%d 不是素数\n",n);
	}
}

	int sushu(int n)
	{
		int flag=1,i;
		for(i=2;i<n/2&&flag==1;i++)    //i为除数 
		if(n%i==0)
		flag=0;
		return(flag);                 //重置flag
	}