Hi Rahul Gurung! On 8/8/2018 9:37 AM, Rahul Gurung wrote: > In colleges, we are taught to use header files like iostream.h in cpp to > use various functions, but while diving in LO code (specifically java > and cpp tests)Â i found that we don't mention those header files, why so? Please be more specific: like which .cpp file uses what, and which header you expect but don't find. Most probably you simply don't see that the expected header is mentioned in a wrapper header already included. -- Best regards, Mike Kaganski