从输入复制到输出文本文件

Question

大家好，这是我的功能代码，但它不能正常工作，它应该从 input.txt 读取数字并计算每行中偶数、奇数的总和，然后计算质数的结合（正确) 并复制所有素数到 output.txt

这是我的代码，问题是：它还会复制非素数的数字。非常感谢！！！

#include "stdafx.h"
#include<iostream>
#include<fstream>
#include<string>
#include<sstream>
using namespace std;


int _tmain(int argc, _TCHAR* argv[])
{
    ifstream read;
    read.open("input.txt");
    ofstream write;
    write.open("output.txt");
    string line;
    int even, odd, primeXprime;

    if(read.fail())
        cout << "Cant open input.txt" << endl;

    int x, p = 0;

    if(read.is_open())
    {
        while(read, line)
        {
            even = odd = 0;
            primeXprime = 1;
            istringstream sRead(line);

            while(sRead >> x)
            {
                if(x % 2 == 0)
                    even += x;

                if(x % 2 != 0)
                    odd += x;

                for(int i = 2; i <= x; i++)
                {
                    if(x % i == 0)
                        p++;

                    if(p == 2)
                    {
                        primeXprime *= x;
                        write << x << " ";
                        p = 0;
                    }
                    else
                        break;
                }
            }

            cout << "Sum of even numbers are: " << even << endl;
            cout << "Sum of odd numbers are: " << odd << endl;
            cout << "Sum of prime numbers are: " << primeXprime << endl;
            cout << endl;
        }

        read.close();
        write.close();
        system("pause");
        return 0;
    }
}

Answer 1

问题出在您的素数测试算法上，您无法确定一个数是否为素数，除非您将它除以 [2,Sqrt(n)] 范围内的所有数字

在行“if(p == 2)”中，您假设它不会除以范围内的任何数字。

将整个 for 循环替换为

for(int i = 1; i < x; i++)
{
               if(x % i == 0)
                    p++;
}
if(p < 2)
{
    primeXprime *= x;
    write << x << " ";
}
p = 0;

从输入复制到输出文本文件

Copying from input to the output text file

c++

file-io

primes