fread和fwrite是否失败?如何处理呢? [英] do fread and fwrite have failure? how to handle this?

问题描述

当我使用fread(C语言)从文件中读取时，fread的返回值有时会为0.

when I read from a file using fread (C language), the return value of fread sometimes would be 0.

按照手册建议:

fread()和fwrite()返回成功读取的项目数，或者书面

fread() and fwrite() return the number of items successfully read or written

我必须编写这样的代码吗?

do I have to write code like this?

int bytes_read;
while((bytes_read = fread(buffer, sizeof(int), 1, fp)) == 0) {

}

我们是否总是需要检查fread或fwrite是否成功?

do we always have to check whether fread or fwrite succeeded?

推荐答案

不，如果 fread 或 fwrite 返回的内容较少，则没有必要进行这样的重试循环超出预期的读取或写入记录数.也就是说，stdio与可能导致短"读取或写入的低级 read 和 write 操作不同.

No, there's no sense in doing a retry-loop like this if fread or fwrite returns fewer than the expected number of records read or written. That is to say, stdio is not like the low-level read and write operations that can result in "short" reads or writes.

如果 fread 返回的记录少于请求的记录数，则说明您遇到了EOF或严重的读取错误.您可以通过检查 feof()和 ferror()来区分它们.

If fread returns fewer than the requested number of records, you've either hit EOF or a serious read error. You can distinguish between them by checking feof() and ferror().

类似地，如果 fwrite 返回的记录少于请求的记录数，则说明磁盘空间不足或出现严重的写入错误.

Similarly, if fwrite returns fewer than the requested number of records, you've either run out of disk space or hit a serious write error.

在任何情况下，由于缓冲stdio使得基本上无法知道成功写入了多少，因此，如果遇到写入错误，通常需要考虑文件丢失并中止整个操作.

In any case, due to buffering stdio makes it essentially impossible to know how much was successfully written, so if you encounter a write error, you usually need to consider the file lost and abort the whole operation.

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