Reading a C file, read an extra line, why?

Question

I don\'t know exactly why a file pointer reads an extra line from a file, specifically the last line, here is the code:

FILE *fp ;
fp = fopen (\"mac_ip.txt\"         


        

Answer 1

FILE *fp ;
int mac;
char ip[15];

fp = fopen ("mac_ip.txt", "r") ;
if (!fp) return;

while(1){
    if (fscanf(fp,"%i",&mac) < 1) break;
    if (fscanf(fp,"%s",ip) < 1) break;

    printf("MAC: %i\n",mac);
    printf("IP: %s\n",ip);  
}
fclose (fp);

fscanf() returns the number of assignments it mad (or -1 on eof). By using the return value, you don't need the eof() function. BTW I don't think you can read a MAC address into an int. Maybe you need to read that into a string, too ?

Explanation: feof() does not do what the OP expects. feof() should only be inspected after one of the file operations failed. In most cases you don't need feof().