I want to ask that why %id is required

Answer 1

Pls specify the language in ur tag section.
Considering it to be C ,
There's no format specifier called "%id".

If u mean "%ld" ,then it is the format specifier for "long int".This format specifier is used when u want to store a large integer which could not be stored in int.

Answer 2

Yash Patil , The best thing to get help is to clear the question from any doubt. So it would be helpful to not only see '%id' but to get an idea from the complete expression or code. Just post it here. Thanks!