Programming

Hello everybody... In my client - server application I decided to save user name and password in a file by the system call creat(), write().

Code:

 recv(i,buf,sizeof(buf),0);
             result=write(ds_user,buf,sizeof(buf));
                          if (result==-1){
                              printf("error on write");
                              exit(1);
                            }

Now there is a problem in the client-autentication and the next registration-autentication becouse I don't know very well how to manage the file:
This is the autentication code but it's not work

Code:

recv(i,buf,sizeof(buf),0);
char buffer[40];
result1=(ds_user,buffer,40);
printf("%s",buffer);
if (result1==-1){
   printf("error on read");
   exit(1);
 }
   if (strcmp(buf,buffer)==0){
    send(i,"/ok",MAX,0);

where the problem?? is there someone that has got some good example with I/O file?? For example if I want to start reading or writing not at the begin but for example in the middle of the file or in the second row or at the fifth word???
Thank you very much!

This line:

Code:

result1=(ds_user,buffer,40);

...what is it even supposed to do? I can't tell. It looks vaguely like a function call but there's no function! I'm shocked it compiles.

For file I/O, see man pages for fopen, fclose, and fgets. if it's a text file it's best to read line by line since you'll have no idea what line you'll end up in when you seek.

Hi.
I think comma operators in a list (essentially) throw away everything except the right-most value ... cheers, drl

Ok, first I must read a lot of slide in which there is I/O file, after that I'll start to write code!;-)

You could also read the manual pages for the functions I suggested, they will be helpful.

It is part of the C standard; commas are sequence points. Plus, the OP forgot the write(

Hi, jim.
Thanks for reply -- it's good to know and use the correct terminology.

For those wishing to read more, see Sequence point - Wikipedia, the free encyclopedia ... cheers, drl