将size_t转换为整数(c++)

I've been trying to make a for loop that will iterate based off of the length of a network packet. In the API there exists a variable (size_t) by event.packet->dataLength. I want to iterate from 0 to event.packet->dataLength - 7 increasing i by 10 each time it iterates but I am having a world of trouble.I've been trying to make a for loop that will i