I have a following piece of code

printf("creating log file ... ");
result = ee_log.init();
if(result == true)
{
printf("success \n");
}
else if(result == false)
{
perror("error - > Error in opening log file.");
return false;
}

but while running the program, I get "error - > Error in opening log file." printed before "creating log file ... ". Is this something to do with blocking system calls ?

It has to be like this

creating log file ...
error - > Error in opening log file.: Permission denied

But What I am getting in the terminal is

error - > Error in opening log file.: Permission denied
creating log file ...

Not really sure, but is perror outputting to stdout or stderr ? it may be related, because I think the printf is to stdout, and perror is to stderr... I am not sure how to change the order, but I think there would be a way. If you want you can redirect one or the other by redirecting 1> /path/stdout.txt 2> /path/stderr.txt

more info, and how to redirect both can be found here:
http://www.cpqlinux.com/redirect.html

hope this helps

It's because stdout is line buffered and stderr is not buffered at all. So the "creating log file..." will be printed when the program terminates. If you add a \n to the "creating log file..." message, the buffer will be flushed.

If you don’t want the linefeed, you can force a buffer flush with