C++ ifstream，行尾并移动到下一行？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/477408/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
ifstream, end of line and move to next line?
提问by Martin York
how do i detect and move to the next line using std::ifstream?
我如何使用 std::ifstream 检测并移动到下一行？
void readData(ifstream& in)
{
string sz;
getline(in, sz);
cout << sz <<endl;
int v;
for(int i=0; in.good(); i++)
{
in >> v;
if (in.good())
cout << v << " ";
}
in.seekg(0, ios::beg);
sz.clear();
getline(in, sz);
cout << sz <<endl; //no longer reads
}
I know good would tell me if an error happened but the stream no longer works once that happens. How can i check to see if i am at the end of line before reading another int?
我知道好会告诉我是否发生错误，但一旦发生错误，流就不再有效。在读取另一个 int 之前，如何检查我是否在行尾？
回答by Martin York
Use ignore() to ignore everything until the next line:
使用 ignore() 忽略所有内容，直到下一行：
in.ignore(std::numeric_limits<std::streamsize>::max(), '\n')
If you must do it manually just check othe character to see if is '\n'
如果您必须手动执行此操作，只需检查其他字符以查看是否为 '\n'
char next;
while(in.get(next))
{
if (next == '\n') // If the file has been opened in
{ break; // text mode then it will correctly decode the
} // platform specific EOL marker into '\n'
}
// This is reached on a newline or EOF
This is probably failing because you are doing a seek before clearing the bad bits.
这可能会失败，因为您在清除坏位之前进行了搜索。
in.seekg(0, ios::beg); // If bad bits. Is this not ignored ?
// So this is not moving the file position.
sz.clear();
getline(in, sz);
cout << sz <<endl; //no longer reads
回答by sth
You should clear the error state of the stream with in.clear();after the loop, then the stream will work again as if no error happened.
您应该in.clear();在循环之后清除流的错误状态，然后流将再次工作，就好像没有发生错误一样。
You might also simplify your loop to:
您还可以将循环简化为：
while (in >> v) {
cout << v << " ";
}
in.clear();
The stream extraction returns if the operation succeeded, so you can test this directly without explicitly checking in.good();.
如果操作成功，流提取将返回，因此您可以直接对此进行测试，而无需显式检查in.good();。
