c++ - c++ usigned long long range vs mysql unsigned bigint range

Question

I have a MySQL UDF that returns unsigned long long value. When i call this function in MySQL and the Data has been saved in database, MySQL returns warning:
"BIGINT UNSIGNED value is out of range".
How can i save large unsigned long long numbers in database?

MySQL version: 5.5.43
OS : Ubuntu 14.04

please help.