c++ - 从C++中的istream对象读取时如何检测空行?

2022-01-07 00:00:00 string input stream c++ istream

如何检测一行是否为空?

How can I detect if a line is empty?

我有:

1
2
3
4

5

我正在用 istream r 阅读这篇文章所以:

I'm reading this with istream r so:

int n;
r >> n

我想知道什么时候到达 4 和 5 之间的空间.我尝试读取为 char 并使用 .peek() 来检测 但这会检测到数字 1 之后的 .上述输入的翻译是: 1 2 3 4 5 如果我是对的...

I want to know when I reach the space between 4 and 5. I tried reading as char and using .peek() to detect but this detects the that goes after number 1 . The translation of the above input is: 1 2 3 4 5 if I'm correct...

因为我要操作整数，所以我宁愿将它们读为整数而不是使用 getline 然后转换为整数...

Since I'm going to manipulate the ints I rather read them as ints than using getline and then converting to int...

推荐答案

它可能看起来像这样:

#include <iostream>
#include <sstream>
using namespace std;

int main()
{
    istringstream is("1
2
3
4

5
");
    string s;
    while (getline(is, s))
    {
        if (s.empty())
        {
            cout << "Empty line." << endl;
        }
        else
        {
            istringstream tmp(s);
            int n;
            tmp >> n;
            cout << n << ' ';
        }
    }
    cout << "Done." << endl;
    return 0;
}

输出:

1 2 3 4 Empty line.
5 Done.

希望这会有所帮助.

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