Hi,
I want to create a function which will tell if me the last packet i got from the server is identical to the one i got now.
I thought about put in an array and just compare the two but it will be very inefficient.
So, a checksum or a signature implementation will ( i think ...) do the work.
But how do i make a checksum for let say a const char * data type?

Any help will be thankful!

any hash function will do.

examples:
a fast one (32bit): djb2(xor) from http://www.cse.yorku.ca/~oz/hash.html
a strong one (64bit, less collisions): http://www.larc.usp.br/~pbarreto/WhirlpoolPage.html

but a hash makes sense only if you want to compare several times. if you only need to compare to the last packet, you should use memcmp(). or make the server stop sending multiple packets of the same contents