Can baking powder be subsititued with regular sugar to make powdered sugar?

One cup granulated sugar, one tablespoon corn starch, in food processor until powdered texture. I have made this and it's great. BB

Corn starch (or tapioca starch) is the customary additive in powdered sugar. If you're making a substitute at home, though, you don't need to add anything, just process sugar until its powdery.

No. If you have a food processor or blender, throw gran sugar and blend/process till fine.

No. Powdered sugar is just very finely ground sugar.