Question

这有什么问题吗？这部分代码与其他可用的选项格式相同，但这一部分不能写入输出文件。

else if (choice1 == 4) {
  int nodes[100];
  int b = 0;
  int number;

  cout << "Please give the nodes that you want to include in the sub-graph.\n"
       << "(press -1 to stop input): ";

  do {
    cin >> number;
    nodes[b++] = number;
    b++;
  } while (number != (-1));

  outfile.open("output.txt", ::ofstream::in | ::ofstream::out | ::ofstream::app);

  if (outfile.is_open()) {
    outfile << "nodes[0]" << nodes[1] << nodes[2];
  }

  cout << endl << "Report stored in file: output.txt." << endl;
}

Answer 1

你有：

do {
  cin >> number;
  nodes[b++] = number;
  b++;
} while (number != (-1));

我在这个do-while循环中看到了代码的几个问题。

您将数字-1存储在nodes中。根据我的理解，-1是一个停止的信号。存储它没有意义。
您在循环中递增b两次。也许这是你的意图，也许这是一个疏忽的错误。

上面的代码块可以更改为：

while (true)
{
  cin >> number;
  if ( number == -1 )
  {
    break;
  }
  nodes[b++] = number;
}

Answer 2

似乎一切都是正确的，但你错过了一些东西。为了使更改生效，您需要正确关闭文件。

使用outfile.close();

else if(choice1==4) 
{
    int nodes[100];
    int b=0;
    int number;
    cout<< "Please give the nodes that you want to include in the sub-graph.\n (press -1 to stop input): ";

    do
    {
        cin>>number;
        nodes[b++]=number;
        b++;
    }
    while(number!= (-1));

    outfile.open ("output.txt", ::ofstream::in | ::ofstream::out | ::ofstream::app);
    if (outfile.is_open())
    {
        outfile<<"nodes[0]"<<nodes[1]<<nodes[2];
    }
    outfile.close();
    cout<<endl<<"Report stored in file: output.txt."<<endl;
}

写入输出文件

2 个答案: