#include

//让n被i除(i的值从2到n-1)

int main()

{

int n,i;

printf("please enter a integer number,n=?");

scanf("%d",&n);

for(i=2;i<=n-1;i++)

if(n%i==0) break;

if(i

",n);

else printf("%d is a prime number.

",n);

return 0;

}

*******************************************************************************************

#include

#include

//让n被i除(i的值从2到根号n)

int main()

{

int n,i,k,a=0;

printf("please enter a integer number,n=?");

scanf("%d",&n);

k=sqrt(n);

for(i=2;i<=k;i++)

if(n%i==0)break;

if(i<=k)printf("%d is not a prime number.

",n);

else printf("%d is a prime number.

",n);

return 0;

}