prime.cpp

编制具有如下原型的函数prime

#include<iostream>
#include<math.h>
using namespace std;

bool prime(int n)
{
	int i;
	for(i=2;i<=sqrt(n);i++)
	{ 
		if((n%i)==0)  return false; 

	} 
}
int main()
{
	int first=3,second;
	int num;
aa:	cout<<"请输入一个大于4的偶数：";
	cin>>num;
	cout<<endl;
	if(num%2!=0||num<=4) goto aa;
	while(first<(num/2))
	{
		while(first<(num/2))
		{
			if(prime(first)) break;
			else first++;
		}
		second=num-first;
		if(prime(second)) 
			cout<<num<<"="<<first<<"+"<<second<<endl;
		first++;
		

	}
	return 1;
}