在 C++ Builder 中获取文本文件的第二行

Question

My text file looks like this

Fruit 
Vegetable

And I need the function to return Vegetable

This is the code I tried to use and get "Vegetable":

String getItem()
{
ifstream stream("data.txt");

stream.ignore ( 1, '\n' );

std::string line;
std::getline(stream,line);

std::string word;
return word.c_str();
} 

Then I did this to try and put the second line into an edit box:

void __fastcall TMainForm::FormShow(TObject *Sender)
{
    Edit1->Text = getItem();
}

For some reason, when I run the code the Edit Box eventually just has nothing in it, completely blank.

Answer 1

The 1st parameter of istream::ignore() is expressed in characters , not lines . So, when you call stream.ignore(1, '\n') , you are ignoring only 1 character (ie, the F of Fruit ), not 1 line .

To ignore a whole line, you need to pass in std::numeric_limits<streamsize>::max() instead of 1 . That tells ignore() to ignore all characters until the specified terminator ( '\n' ) is encountered.

Also, you are return 'ing a blank String . You are ignoring the line that you read with std::getline() .

Try this instead:

#include <fstream>
#include <string>
#include <limits>

String getItem()
{
    std::ifstream stream("data.txt");

    //stream.ignore(1, '\n');
    stream.ignore(std::numeric_limits<streamsize>::max(), '\n');

    std::string line;
    std::getline(stream, line);

    return line.c_str();
    // or: return String(line.c_str(), line.size());
}