2018年5月10日 · Well, from the manpage we can see that ftell and fseek use type long int to represent offsets (positions) in a file, and may therefore be limited to offsets which can be represented in a long int. (Type long int is not guaranteed to hold values larger than 2**31-1, limiting the maximum offset to 2 gigabytes).

2023年4月6日 · ftell returns the current value of the file position indicator, and fgetc does advance the file position indicator within the loop. But this program is wrong. For a stream opened in text mode ( "r" ), the return value of ftell cannot be used portably for anything else except for seeking to a previous position.

2014年1月14日 · The ftell() function obtains the current value of the file position indicator for the stream pointed to by ...

fseek(f, 0, SEEK_END); // seek to end of file size = ftell(f); // get current file pointer fseek(f, 0, SEEK_SET); // seek back to beginning of file // proceed with allocating memory and reading the file Linux/POSIX: You can use stat (if you know the filename), or fstat (if you have the file descriptor). Here is an example for stat:

2018年3月6日 · And for a text stream, 7.21.9.4 The ftell function, paragraph 2 states: The ftell function obtains the current value of the file position indicator for the stream pointed to by stream. For a binary stream, the value is the number of characters from the beginning of the file.

2013年5月22日 · on ftell/fseek. ftell() and fseek() are limited to 32 bits (including sign bit) on the vast majority of 32-bit architecture systems. So when there is large file support you run into this 2GB issue. POSIX.1-2001 and SysV functions for fseek and ftell are fseeko and ftello because they use off_t as the parameter for the offset.

2012年5月18日 · From the documentation of ftell: or binary streams, the value returned corresponds to the number of bytes from the beginning of the file. For text streams, the value is not guaranteed to be the exact number of bytes from the beginning of the file, but the value returned can still be used to restore the position indicator to this position using ...

2014年6月27日 · I have a file. I read the size of file. Then I loop reading two bytes at a time until I get to the end of the file. After every read operation I increment the current position by 2, however the pos...

2014年6月3日 · ftell does not return the total size of the file; it returns the current read or write position within the file. You call ftell immediately after opening the file, so that position is the very beginning of the file.

2011年10月9日 · If you inspect errno immediately after the call to ftell you will discover that it has the value ESPIPE, which means "You can't do that to a pipe." If you're trying to read all of the output from the command into a single char* buffer, the only way to do it is to repeatedly call one of the read functions until it indicates end-of-file, and ...