C++ 文件处理:ios::app 和 ios::ate 之间的区别?

2021-12-09 00:00:00 file c++ fstream c++-standard-library

在写入文件时,ios::ateios:app 之间有什么区别.
在我看来,ios::app 使您能够在文件中移动,而使用 ios::ate 它只能在文件的末尾读/写文件.这是正确的吗?

What's the difference between ios::ate and ios:app when writing to a file.
In my view, ios::app gives you the ability to move around in the file, whereas with ios::ate it can only read/write at the end of the file. Is this correct?

推荐答案

正好相反.当ios::ate 被设置时,初始位置将是文件的末尾,但您可以在此后自由查找.当设置 ios::app 时,所有 输出操作都在文件末尾执行.由于所有写入都隐含地在查找之前,因此无法在其他地方写入.

It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write elsewhere.

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