8-4.cpp

能判断二次函数是否有根

/*3208006411*/
#include<stdio.h>
void main()
{
int prime(int);
int n;
printf("\ninput an integer:");
scanf("%d",&n);
if(prime(n))
 printf("\n%d is a prime.\n",n);
else
 printf("\n%d is not a prime.\n",n);
 }
int prime(int n)
{int flag=1,i;
for(i=2;i<n/2&&flag==1;i++)
 if(n%i==0)
    flag=0;
 return(flag);
 }