如果单元格不是公式，如何执行替换？

I want to do a mass replacement in a folder with a lot of excel files. Some files are in sub folders. But I want to replace only if the cell I'm replacing in is not a formula. I think I could do that by checking if there is an "=" as the first char of the cell, but I don't know how to code it. So far I have this:I want to do a mass replacement in a folder wit