求各位大师指点！！！！！！

Question

以下是代码#include
#include
#include
using namespace std;
int main()
{
long a,b,l=0;
cout<<"please input two numbers:\n";
cin>>a>>b;
cout<<"primes from"< if(a==2)
cout if(a%2==0)
a++;
for(long m=a;m {
int sqrtm=sqrt((long double)m);
int i;
for(i=2;i if(m%i==0)
break;
if(i>sqrtm)
{
if(l++%10==0)
cout<<endl;
cout<<setw(5)<<m;
}
}
}
这个是为了求从A到B的素数（只能被本身和1整除的数）但是输入1到100 它不会输出2反而会输出1.这个怎么改进？ 求各位大师教教，才开始学C++。先在这里拜谢了。

Answer 1

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
{
    long a, b, l = 0;
    cout << "please input two numbers:\n";
    cin >> a >> b;
    cout << "primes from" << a << " to " << b << endl;
    for(long m = a; m < b; m++)
    {
        int sqrtm = sqrt((long double)m);
        int sign = 1;
        for(int i = 2; i <= sqrtm; i++)
        {
            if(m % i == 0)
            {
                sign = 0;
                break;
            }
        }
        if(sign)
        {
            if(l++%10==0)
                cout<<endl;
            cout<<setw(5)<<m;
        }
    }
    return 0;
}