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Why do I need extern C?
the extern keyword is used to extend the visibility of variables/functions. Since functions are visible throughout the program by default, the use of extern is not needed in function declarations or definitions. Its use is implicit. When extern is used with a variable, it’s only declared, not defined.
Why the C++ is superset of C?
Answer: When he designed C++, he added OOP (Object Oriented Programming) features to C without significantly changing the C component. Thus C++ is a “relative” (called a superset) of C, meaning that any valid C program is also a valid C++ program.
What is D and F in C?
%d and %f are format specifiers. %d is used for integer(-3,-100,3,100,etc). And %f is used for float(10.6,-39.0,etc).
Is it bad to mix C and C + +?
Yes it’s bad to mix C and C++, any the reason has nothing to do with performance or security: * a C++ programmer expects all code to behave like C++. So when you mix C++ and C, you break both programmers expectations on how things should work.
How can I compile mixed C and C + + code?
Instead, just create the application as C++ and link in the C code whose runtime is a subset of the C++ runtime. I should clarify that all this means is compiling your C code with the C++ compiler. It takes care of all of the above for you.
Why do I get linker errors when I mix C and C + +?
If you didn’t get your extern “C” right, you’ll sometimes get linker errors rather than compiler errors. This is due to the fact that C++ compilers usually “mangle” function names (e.g., to support function overloading) differently than C compilers.
Can you use C and C + + in the same program?
Using Oracle Developer Studio compilers, you can therefore use Standard I/O functions freely in both C and C++ code in the same program. The C++ standard says you can mix Standard I/O functions and IOstream functions on the same target “stream”, such as the standard input and output streams. But C++ implementations vary in their compliance.