文件处理读取多行

Question

有人可以帮助我如何在文件处理c ++中多行？我想阅读从search up to 3 next line开始的行。

ifstream fileInput;
fileInput.open("D:\\devc++\\program\\sample.txt");
string lines, search;
cout << "Enter employee number to search for: ";
cin >> search;
  while(!fileInput.eof()){
      getline(fileInput,lines);
      if(lines.find(search)!=string::npos)
        {
             cout << "Found " << lines << endl;
             cout<<"\n";
        }

 }

Answer 1

如下所示更改您的代码，如果您想在下面的代码行search下面找到该代码行，那么您想要打印下面的3行代码。

ifstream fileInput;
fileInput.open("D:\\devc++\\program\\sample.txt");
string lines, search;
cout << "Enter employee number to search for: ";
cin >> search;
  int found = 0;
  while(!fileInput.eof()){
      getline(fileInput,lines);
      if(found > 0 || lines.find(search)!=string::npos)
        {
             cout << "Found " << lines << endl;
             cout<<"\n";
             found ++;
        if(found > 3)
           found = 0;
        }

 }

更好地纠正您的代码，如下所示

 //while(!fileInput.eof()){
   while(getline(fileInput,lines)){
  //getline(fileInput,lines);
  if(found > 0 || lines.find(search)!=string::npos)
    {
         cout << "Found " << lines << endl;
         cout<<"\n";
         found ++;
    if(found > 3)
       found = 0;
    }