C++ ifstream，字节读取？

ifstream, bytes read?

提问by user230821

How do you get how many bytes were read with the ifstream::read function?

你如何获得使用 ifstream::read 函数读取的字节数？

Tell is saying the file is 10 bytes and windows says it is 10 bytes too but there are only 8 bytes in the file so when I read it, it is only reading the 8 bytes so I end up with too large of a buffer.

Tell 说文件是 10 个字节，Windows 说它也是 10 个字节，但文件中只有 8 个字节，所以当我读取它时，它只读取 8 个字节，所以我最终得到了太大的缓冲区。

回答by Alex B

You can find out by calling gcount()on a stream immediately after you read.

您可以通过gcount()在阅读后立即调用流来查找。

ifs.read(buf, sizeof buf);
std::streamsize bytes = ifs.gcount();

回答by AraK

There is a function called readsome(...)that does what you want:

有一个名为的函数readsome(...)可以执行您想要的操作：

streamsize readsome ( char* s, streamsize n );

Return Value The number of characters extracted.

返回值 提取的字符数。