How does C language deal with the random access number of fseek () and ftell ()?

This article mainly introduces the relevant knowledge of "how C language deals with the random access number of fseek () and ftell ()". The editor shows you the operation process through an actual case. The operation method is simple, fast and practical. I hope this article "how C language deals with the random access number of fseek () and ftell ()" can help you solve the problem.

With the fseek () function, you can think of a file as an array, moving directly to any byte in the file opened by fopen (). Let's create a program called reverse.c to demonstrate the use of fseek () and ftell (). Note that fseek () takes three parameters and returns a value of type int; the ftell () function returns a value of type long, indicating the current location in the file.

/ * reverse.c-- displays a file in reverse order * / # include # include # define CNTL_Z '032' / * eof marker in DOS text files * / # define SLEN 81int main (void) {char file [SLEN]; char ch; FILE * fp; long count, last; puts ("Enter the name of the file to be processed:"); scanf ("% 80s", file) If ((fp = fopen (file, "rb")) = NULL) {/ * read-only mode * / printf ("reverse can't open% sn", file); exit (EXIT_FAILURE);} fseek (fp, 0L, SEEK_END); / * go to end of file * / last = ftell (fp); for (count = 1L; count)