The read function returns the number of bytes read (up to the maximum that you specify), -1 on error, or zero if the end of the file has been reached.

read函数返回读取的字节数（最高为您指定的最大值）；或者 -1，表示错误；或者0，如果已经到达文件末尾。

youdao

The read function returns the number of bytes read (up to the maximum that you specify), -1 on error, or zero if the end of the file has been reached.

read函数返回读取的字节数（最高为您指定的最大值）；或者 -1，表示错误；或者0，如果已经到达文件末尾。

youdao