2017年4月3日 · Since read() and lseek() are system calls, they shall correspond to changes in updated file if kernel/OS buffer regularly syncs with file in Hard disk. But that is not the case. The changes in file are not reflected from read(), instead it continues to print the initial content.

2012年2月19日 · Use fseek when using the C stdio library. Use lseek when using low-level POSIX file descriptor I/O. The difference between the various seek functions is just the kind of file/stream objects on which they operate. On Linux, seekg and fseek are probably implemented in …

2010年10月18日 · Regardless, lseek and fseek aren't going to jump to the correct spot unless you know where that is. Additionally, if you increase the record size (for instance when you add 1 to 9 and get 10), you're going to have troubles.

2013年11月5日 · Yes, you can use lseek(): off_t lseek(int fd, off_t offset, int whence); The lseek() function repositions the offset of the open file associated with the file descriptor fd to the argument offset according to the directive whence as follows: SEEK_SET. The offset is set to offset bytes. SEEK_CUR. The offset is set to its current location plus ...

2012年1月17日 · I also noticed that the standard input version was the one you said was working correctly. If you're having trouble with the FILE * version, I suspect the fopen() call is failing, so make sure you check the return value from fopen().

2018年8月28日 · Since you didn't check that the open() succeeded, the most likely problem is that you didn't open the file successfully, and therefore the lseek() fails and reports -1. You've only allowed for a 9-character file name (plus terminal null byte); that isn't very long!

2019年9月23日 · I have written a structure Student into a file and read the whole structure to the console. Now, I want to reposition the file pointer to read information about a specific student. I want to use sy...

2019年9月2日 · I tried to use the system call lseek() to get back the beginning of a file or reach the end of the file. The exact code I used is: int location = lseek(fd, 0, SEEK_SET) //get back to the beginnin...

2017年1月6日 · The lseek() function allows the file offset to be set beyond the end of the file (but this does not change the size of the file). If data is later written at this point, subsequent reads of the data in the gap (a "hole") return null bytes ('\0') until data is actually written into the gap.

2016年10月27日 · lseek() does not work from a filename. It expects an integer file handle. Try stat() instead. Additionally, don't use a pointer return value.