CPP CPP Interoperability & System Programming 1

Question 1

What is the primary purpose of extern "C" in C++?

Accepted Answer

To prevent name mangling so C code can link to C++ functions

Answer

extern "C" instructs the C++ compiler to use C linkage, preventing name mangling so the symbol can be called from C code.

Question 2

Which two techniques are commonly used to prevent multiple inclusions of a header file?

Accepted Answer

Both #pragma once and #ifndef/#define/#endif

Answer

Both the portable #ifndef/#define/#endif include guard pattern and the widely-supported #pragma once compiler extension prevent double inclusion.

Question 3

When calling a C library that allocates memory, how must that memory be freed in C++?

Accepted Answer

Use free()

Answer

Memory allocated by C library functions using malloc/calloc must be released with free(), not delete, to avoid undefined behavior.

Question 4

What does the __cplusplus predefined macro indicate?

Accepted Answer

Whether code is compiled as C++ and which standard version is active

Answer

The __cplusplus macro is set by C++ compilers to an integer value representing the active standard, such as 201703L for C++17.

Question 5

What is C++ name mangling?

Accepted Answer

The compiler encoding of a function's full signature into its binary symbol name

Answer

Name mangling encodes the full function signature (including parameter types) into the binary symbol name to support function overloading.

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