Which of the following is the correct syntax to include a user-defined header file in C++ ?
In C++, the #include preprocessor directive is used to include header files in the source code. When including a user-defined header file, the syntax should use double quotes " ".
For example, if your user-defined header file is named "userdefined.h," you should use the syntax #include "userdefined.h" to include it in your C++ program.