Question

With the use of an example for each, answer the following questions on C++ header files: 1- What is the purpose of a C++ header file? Your explanation should include reference to typical header file content. 2-How is it possible to avoid multiple inclusions of the same file? 3- What are the benefits of conditional compilation?

Answer 1

1. Header files contain definitions of Functions and Variables, which is imported or used into any C++ program by using the pre-processor #include statement.

The purpose of C++ if we want to use any function in our C++ program then first we need to import their definition from C++ library, for importing their declaration and definition we need to include header file in program by using #include. Header file include at the top of any C++ program.

For example if we use clrscr() in C++ program, then we need to include, conio.h header file, because in conio.h header file definition of clrscr() (for clear screen) is written in conio.h header file.

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3. Benifit of conditional compilation are

By conditional compile I mean using #ifdefs to only compile certain bits of code in certain conditions. The #defineds themselves may be in either a common header file

• header guards
• conditional implementationdebug specific checks
• per suggestion: extern "C" { and } so that the same headers may be used by the C++ implementation and by the C clients of the API

2.

1. There are many different platforms that I use.
2. I wonder if there is a simple solution, i.e., without using cmake, etc.
3. I also use cross compilation for coprocessors.
4. I want the flags used in compilation of the utility functions to be same as the flags used in compilation of user codes.

2. it is possible to avoid multiple inclusion of same file :

1. There are many different platforms that can be use.
2. wonder if there is a simple solution, i.e., without using cmake, etc.
3. also use cross compilation for coprocessors.
4. want the flags used in compilation of the utility functions to be same as the flags used in compilation of user codes.