91Ó°ÊÓ

include void friendly( ); void shy(int audience_count); int main( ) { using namespace std; friendly( ); shy(6); … # What is the output of the following program? #include void friendly( ); void shy(int audience_count); int main( ) { using namespace std; friendly( ); shy(6); cout << "One more time:\n"; shy(2); friendly( ); cout << "End of program.\n"; return 0; } void friendly( ) { using namespace std; cout << "Hello\n"; } void shy(int audience_count) { using namespace std; if (audience_count < 5) return; cout << "Goodbye\n"; } The \(\mathrm{C}++\) Standard says that you can omit the return \(\theta\) in the main part, but many compilers still require it.

Are you required to have a return statement in a void function definition?

Write a definition for a void function that has three arguments of type int and that outputs to the screen the product of these three arguments. Put the definition in a complete program that reads in three numbers and then calls this function.

Is a call to a void function used as a statement or is it used as an expression?

Write a void function definition for a function called zero_both that has two reference parameters, both of which are variables of type \(i n t,\) and sets the values of both variables to \(\theta\)

Write a void function definition for a function called add_tax. The function add_tax has two formal parameters: tax_rate, which is the amount of sales tax expressed as a percentage, and cost, which is the cost of an item before tax. The function changes the value of cost so that it includes sales tax.

Can a function that returns a value have a call-by-reference parameter? May a function have both call-by-value and a call-by-reference parameters?

Can a function definition appear inside the body of another function definition?

Can a function definition contain a call to another function?

Give a precondition and a postcondition for the predefined function sqrt, which returns the square root of its argument.