判断素数

#include<iostream>#include<cmath>using namespace std;bool primenumber(unsigned);void main(){unsigned value;cout<<"input a number:"<<endl;cin>>value;    if(primenumber(value)){cout<<value<<"是素数"<<endl;}elsecout<<value<<"不是素数"<<endl;}bool primenumber(unsigned value){unsigned a=2;//被除数while(true){if(value%a==0 && a!=value){return false;}if(a>sqrt(value)){return true;}a++;}}