KCodecs
KCodecs provide a collection of methods to manipulate strings using various encodings.
It can automatically determine the charset of a string, translate XML entities, validate email addresses, and find encodings by name in a more tolerant way than QTextCodec (useful e.g. for data coming from the Internet).
Using the Module
Using a KDE module's C++ API requires linking against the module library. The preferred way of consuming the library is through CMake.
Building with CMake
Use the find_package() command to locate the needed module component in the KF6 package:
find_package(KF6 REQUIRED COMPONENTS Codecs)
target_link_libraries(mytarget PRIVATE KF6::Codecs)
For more details, see the Build with CMake overview.