If you mean formatting as in erasing the partition, no. Your Mac partition will remain the same. The only thing that will change is the size of the partition.
If you mean formatting as in erasing the partition, no. Your Mac partition will remain the same. The only thing that will change is the size of the partition.
You need to format the bootcamp partition for Windows and in the process you select the bootcamp partition. IF you select the wrong partition, you will indeed erase your OSX volume. My advise, make sure you have a backup and be careful. It won't erase the OSX partition as a normal course of action, you need to choose the wrong partition but having a backup is always advisable.