fstream进出不存在的文件 [英] fstream in and out on nonexistent file

问题描述

是否可以在ios :: in&都不存在的文件上打开fstream ios :: out而不会出现错误?

Is it possible to open an fstream on a file that does not exist with both ios::in & ios::out without getting an error?

推荐答案

要打开 fstream 在不存在输入和输出(随机访问)但没有出现错误的文件上，您应该提供

To open an fstream on a file that does not exist for input and output (random access) without getting an error, you should provide the flags fstream::in | fstream::out | fstream::trunc in the open (or constructor) call. Since the file does not already exist, truncating the file at zero bytes is no drama.

在打开仅指定 ios::in时不存在的文件时，可能会出现错误，因为您将永远无法从流中读取内容，因此在这种情况下尽早失败将防止以后发生意外失败.

You may want an error when opening a file that doesn't exist when specifying only ios::in since you'll never be able to read from the stream so failing early in this case will prevent surprise failures later on.

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