How to find out nearest whole number of a double variable?

Question

How can I find the nearest whole number (integer) of a given double value?
As like,
double int
6.3 6
8.99 9

Answer 1

𝐊𝐢𝐢𝐛𝐨 𝐆𝐡𝐚𝐲𝐚𝐥 Is my question is right now?

Answer 2

https://code.sololearn.com/c47R9nAcsxR6/?ref=app