如何使用fstream附加到文件fstream :: app标志似乎不起作用 [英] How to append to a file with fstream fstream::app flag seems not to work

问题描述

我只是想写（附加）到日志文件。我在这里查看：

http：//www.cplusplus .com / reference / iostream / fstream / open /

i simply want to write (append) to a logfile. I looked it up here:
http://www.cplusplus.com/reference/iostream/fstream/open/

所以这就是我所做的

#include <fstream>

fstream outfile;

//outfile.open("/tmp/debug.txt" );  // works, simply for writing
outfile.open("/tmp/debug.txt", fstream::app );  // does nothing

outfile << "START" << endl;

outfile.close();

推荐答案

fstream :: app | fstream :: out 而不是 fstream :: app 。如果不指定 out ， app 就没有任何意义（有人可能认为它应该暗示了 out ，但不是）。

fstream::app|fstream::out instead of fstream::app. app doesn't make sense without specifying out (one could think it should have implied out, but it doesn't).

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