It is possible to get the all Non-Unicode characters from pdf text?, If possible which method should i use.
Please define “non Unicode character” precisely as it is not a PDF concept.
Export the PDF as Plain Text, I believe this will convert all characters to UTF-8.
Have you looked at the Preflight "Browse Internal Structure" tool? This shows you details of the fonts.
Here is a better tool that allows you to select text and then it shows the properties.
You can do this pragmatically with the C++ Plug-in SDK. Is this an option?