Question

include using namespace std; namespace sally { void message( ); } namespace { void message( ); } int ma… # What is the output produced by the following program? #include using namespace std; namespace sally { void message( ); } namespace { void message( ); } int main( ) { { message( ); using sally::message; message( ); } message( ); return 0; } namespace sally { void message( ) { cout << "Hello from Sally.\n"; } } namespace { void message( ) { cout << "Hello from unnamed.\n"; } }

Short answer

Answer: The output of the given C++ code is: "Hello from unnamed." "Hello from Sally." "Hello from unnamed."

Step-by-step solution

Analyze the sally namespace

In this C++ program, there is a namespace called sally, which contains a function called message(). This function, when called, prints "Hello from Sally." to the output stream.

Analyze the unnamed namespace

There is also an unnamed namespace in the program, which also contains a function called message(). This function, when called, prints "Hello from unnamed." to the output stream.

Analyze the main function

The main function is the starting point of the program, and it calls the message() functions in different ways. First, it calls message() function without a namespace which will call the function in the unnamed namespace, leading to the output of "Hello from unnamed." Next, it incorporates the usage of "using sally::message;", which means that message() function from sally namespace can be used directly. It then calls message() function again, and this time it will call the function from sally namespace, producing the output "Hello from Sally." Lastly, it calls message() function without using any namespace one more time. Since it is outside of the scope where 'using sally::message;' was present, it will again call the function in the unnamed namespace, leading to the output of "Hello from unnamed."

Determine the final output

Combining all the outputs from step 3, the final output produced by the program will be: "Hello from unnamed." "Hello from Sally." "Hello from unnamed."