Question

这是一个家庭工作问题，所以如果你不是那些我理解的粉丝。这是我的代码：

#include <fstream>
#include <iostream>
#include <string>
using namespace std;

int main()
{
    fstream myfile1("datafile1.txt"); //this just has a bunch of names in it
    fstream myfile2("cmdfile1.txt");  //has commands like "add bobby bilbums"
    ofstream outputFile("outfile1.txt"); //I want to take the "add bobby" command and copy the name into this new file.
    string line;
    if (myfile1.is_open() && myfile2.is_open()) //so I open both files
    {
        if (myfile2, line == "add"); //If myfile2 has an "add" in it
        {
            outputFile.is_open(); //open outputfile
            outputFile << line << endl; //input the line with add in it till the end of that line.
        }
    }
    cout << "\nPress Enter..."; // press enter and then everything closes out.
    cin.ignore();
    outputFile.close();
    myfile2.close();
myfile1.close();
return 0;
}

问题是，虽然outputFile总是为空。它永远不会将cmdfile1中的任何行复制到输出文件中。有谁知道我在这里缺少什么？

Answer 1

尝试更像这样的东西：

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
    ifstream myfile1("datafile1.txt");
    ifstream myfile2("cmdfile1.txt");
    ofstream outputFile("outfile1.txt");
    string line;

    if (/*myfile1.is_open() &&*/ myfile2.is_open() && outputFile.is_open())
    {
        while (getline(myfile2, line))
        {
            if (line.compare(0, 4, "add ") == 0)
            {
                outputFile << line.substr(4) << endl;
            }
        }
    }

    myfile1.close();
    myfile2.close();
    outputFile.close();

    cout << "\nPress Enter...";
    cin.ignore();

    return 0;
}

C ++：无法将输入文件中的行复制到输出文件中

1 个答案: