The basic high-level function for closing files is fclose.
Simply pass this function a stream, and fopen will close it and
break the connection to the corresponding file, first reading any
buffered input and writing any buffered output. If the file was closed
successfully, fclose will return 0; otherwise, it will return
EOF.
It is important to check for errors when you close a stream to which you
are writing. For example, when fclose attempts to write the
output remaining in its buffer, it might generate an error because the
disk is full. Following is an example of closing a file with write
access, while checking for errors.
#include <stdio.h>
int main()
{
FILE *my_stream;
char my_filename[] = "snazzyjazz.txt";
int close_error;
my_stream = fopen (my_filename, "w");
fprintf (my_stream, "Just a little hello from fprintf.\n");
close_error = fclose (my_stream);
if (close_error != 0)
{
printf ("File could not be closed.\n");
}
else
{
printf ("File closed.\n");
}
return 0;
}