How to hard code binary data to string

I want to test serialized data conversion in my application, currently the object is stored in file and read the binary file and reloading the object.

In my unit test case I want to test this operation. As the file operations are costly I want to hard code the binary file content in the code itself.

How can I do this?

Currently I am trying like this,

std::string FileContent = "\00\00\00\00\00.........";

and it is not working.