How to log user defined struct/class object in C++

I need to add logging to a legacy c++ project, which contains hundreds of user defined structs/classes. These structs only contain primary types as int,float,char[],enum.

Content of objects need to be logged ,preferred in human readable way , but not a must, as long as the object could be reconstructed.

Instead of writing different serialization methods for each class, is there any alternative method?