c++ - 使用getline从输入文件打印时如何忽略空行

Question

我正在尝试打印文件的内容，但我不确定如何忽略文件中的空行。

当前代码:

if(option == "-ps"){
        while(getline(instream, str)){
            if(str.length() == 0){
                continue;
            }
            cout << str << endl;   
        }
    }

文件内容

Department meeting | 2019 |10 |29 |9:30 aM  |15 
    Meeting with Bob | 2019 |10 |29 |8:30 aM  |15 
 Meeting with Jim | 2019 |10 |29 |9:00 aM  |15 

 Doctor's appointment | 2019 |10 |29 |10:30 aM  |15 
 Meeting with Bob | 2019 |10 |29 |11:30 aM  |15 
    Lunch meeting with dean | 2019 |10 |29 |11:45 aM  |15 
 Lunch with the guys | 2019 |10 |29 |12:30 pM  |60 
    Lunch with the guys | 2019 |10 |29 |12:30 pM  |60 
 Lunch with the guys | 2019 |10 |29 |12:30 pM  |60 
 Meeting With BOB | 2019 |10 |29 |1:30 pM  |15 

 Chair meeting | 2019 |10 |29 |2:30 PM  |15 
 Meeting WITH Bob | 2019 |10 |29 |3:30 pm  |20 
  Fishing with Donald and Donald|2019|11|30|8:14AM| 115
Fishing with Donald and Billy|  2019|12|11  | 2:45 PM|15
Appointment with Donald|2019  |12|5|8:56PM |115
Appointment with Fred|2019|12|1|8:30PM|50



Lunch|2019|12  | 1|10:58PM |115
Fishing with Bob and Fred|2019 |12| 3| 2:45PM|10
Skiing with Juedes|  2019|12  | 8|9:15 am|60 

我当前的代码将打印出文件内容，但空行仍会打印出来。我试图用第二个 if 语句解决这个问题，但它似乎不起作用。

感谢任何帮助。

Answer 1

逻辑

if(str.length() == 0){
    continue;
}

如果有包含一个或多个空白字符的行将不起作用。也许你正在遇到他们。您可以将其更改为使用:

if ( is_empty_line(line) )
{
    continue;
}

在哪里

bool is_empty_line(const& line)
{
   for (char c : line )
   {
      if ( !std::isspace(c) )
      {
         return false;
      }
   }

   return true;
}

您可以使用 std::all_of以简化该功能。

bool is_empty_line(const& line)
{
   return std::all_of(line.begin(), line.end(), [](char c) { return std::isspace(c); });
}