C Data Types. C types an be classified as:Fundamental (or simple or scalar): A data object of one of these types is a single object. - int, double, char, bool, complex, and the related types (unsigned, short, etc.) ? primitive data types - enumerations ? User-defined Data TypesStructured: Collections of data arrays, structs, unions, classes, valarrays, bitsets, the containers and adapters in STL.