TLH is an extension specific to programming files mainly in the C and C ++ programming languages. TLH files are used to store header files, in this particular case it is a type library. Header files are included with created programs at the beginning of their source code. For TLH files, this is done using the "#import" compiler (preprocessor) directive.

C ++ is a general-purpose multi-paradigm programming language developed by Bjarne Stroustrup.