找到两个x1,x2之间的素数总数,找不到错误？

Question

我需要找到两个数字之间的素数之和,比如x1和x2,但是我无法检测到什么是错误的？例如,如果我输入3和9我会得到15但我得到133!

#include <iostream>
using namespace std;
int prime(int n1, int n2)
{
    int  count =0;
    bool prime = true;

    for (n1; n1 < n2; n1++)
    {
        for (int i = 2; i < n1; i++)
        {
            if (n1 % i == 0) {
                prime = false;
                continue;
            }
            else
                count++;
        }
    }
    return count;

}
int main()
{
    int n1, n2;
    cout << " Enter values for n1 and n2 (n1 must be smaller than n2):   ";
    cin >> n1>>n2;


    cout << " Sum of prime numbers from " << n1 << " and till " << n2 << " inclusively : " << prime(n1, n2) << endl;
    system("pause");
    return 0;
}

Answer 1

你的主要功能是不合适的.这应该是这样的.

int prime(int n1, int n2) {
    int sum = 0;

    for (n1; n1 < n2; n1++) {       
        bool prime = true;
        for (int i = 2; i < n1; i++) {
            if (n1 % i == 0) {
                prime = false;
                break;
            }
        }
        if( prime ) { // current n1 is prime 
            sum = sum + n1;
        }
    }
    return sum;
}

如果你的n1是素数,你不会添加任何东西.