Question

我必须创建一个程序，该程序在A组文件中获取字符串，并将它们与B组的字符串进行比较，创建视频输出，结果等于输出视频文件。群组文件的结构如下：Jhon Smith＆＃39; \ n＆＃39; Fergus McDonald＆＃39; \ n＆＃39; Elizabeth Harris＆＃39; \ n＆＃39;。我有嵌套while循环的问题，最后一个检查A的名字是否等于B的名称似乎工作，但其他两个不是，第一次内循环工作，但然后另一个没有，if条件似乎没有更多的工作，并重复文件元素的数量的文件的所有名称，反之亦然第二组嵌套while循环，我不明白是什么错误

#include <stdlib.h>
#include <string.h>
#include <iostream>
#include <fstream>

using namespace std;

int main() {
    string As, Bs, Cs;
    ifstream A("Group_A.txt");
    ifstream B("Group_B.txt");
    ofstream C("Result.txt");

    if(!A)
    {
        cout<<"Group A does not exist!";
        return -1;
    }
    if(!B)
    {
        cout<<"Group B does not exist!!";
        return -1;
    }
    if(!C)
    {
        cout<<"Failed to create file!!";
        return -1;
    }

    C<<"Elements in A but not in B:"<<endl;
    while(getline (B,Bs))
    { 
      while(getline (A,As))
      { 
        if (As != Bs)
        {
            C<<As<<endl;
        }
      }
      A.clear();
      A.seekg(0);
    }
    A.close();
    B.close();
    C<<endl;

    A.open("Group_A.txt");
    B.open("Group_B.txt");
    C<<"Elements in B but not in A:"<<endl;
    while(getline (A,As))
    {
      while(getline (B,Bs))
      { 
        if (Bs != As)
        {
            C<<Bs<<endl;
        } 
      }
      B.clear();
      B.seekg(0);
    }
    A.close();
    B.close();
    C<<endl;

    A.open("Group_A.txt");
    B.open("Group_B.txt");
    C<<"Elements present in both A and B:"<<endl;
    while(getline (A,As))
    {
      while(getline (B,Bs))
      { 
        if (As == Bs)
        {
            C<<Bs<<endl;
        } 
      }
      B.clear();
      B.seekg(0);
    }

    A.close();
    B.close();
    C<<endl;
    C.close();

    ifstream res("Result.txt");
    while(res >> Cs)
    cout<<Cs<<endl;

     system ("PAUSE");
      return 0;
}

Answer 1

// write a function that load your file
template <class Itr>
void read_file(std::string const& name, Itr to) {
    std::ifstream in(name);
    for (std::string line; std::getline(in, line); *itr++ = std::move(line));
}

// load your files
std::set<std::string> a;
read_file("a.txt", std::inserter(a));
std::set<std::string> b;
read_file("b.txt", std::inserter(b));

// based on what you need use one of set algorithms
// from the standard library
// I assumeed you need the union of the two in the below code
std::vector<std::string> c;
std::set_union(a.begin(), a.end(), b.begin, b.end(), std::back_inserter(c));

// dump the result
std::ofstream out("c.txt");
std::copy(c.begin(), c.end(), std::ostream_iterator(out, "\n"));

Answer 2

问题：

Integer value = order.get(Character.toLowerCase(c));

假设文件A包含1,2,3，文件B包含2,3,4

测试将如下所示：

foreach B in file B
    foreach A in file A
        if (A != B)
            output A

输出文件将包含1,3,1,2,1,2,3

你想要做的是建立文件A和B的集合交集（让我们称之为AnB）。这给你第三个循环。 A和B都是。

将AnB与A进行比较。因此，A中的所有内容都不在B中。是A而不是B.重复B

或者您可以致电std::set_intersection和std::set_difference

2 != 1: true, output 1
2 != 2: false, no output
2 != 3: true, output 3
3 != 1: true, output 1
3 != 2: true, output 2
3 != 3: false, no output
4 != 1: true, output 1
4 != 2: true, output 2
4 != 3: true, output 3

嵌套while循环文件c ++问题

2 个答案: