C++ 如何从文件中读取第一行？

How can i read first line from file?

提问by user2036891

ifstream infile;

string read_file_name("test.txt");

infile.open(read_file_name);

string sLine;

    while (!infile.eof())
    {
        getline(infile, sLine);         
        cout << sLine.data() << endl;
    }

    infile.close();

This program prints all line in the file, but I want to print only first line.

该程序打印文件中的所有行，但我只想打印第一行。

回答by billz

while (!infile.eof())does not work as you expected, eofsee one useful link

while (!infile.eof())没有按预期工作，eof查看一个有用的链接

Minor fix to your code, should work:

对您的代码进行小修，应该可以：

  ifstream infile("test.txt");

  if (infile.good())
  {
    string sLine;
    getline(infile, sLine);
    cout << sLine << endl;
  }

  infile.close();

回答by Dkrtemp

You can try this:

你可以试试这个：

ifstream infile;

string read_file_name("test.txt");

infile.open(read_file_name);

string sLine;

while (!infile.eof())
{
    infile >> sLine;
    cout << sLine.data() << endl;

}

infile.close();

This should print all the lines in your file, line by line.

这应该逐行打印文件中的所有行。