Exam 2 Short Answers

Implement a function void my_swap(int& a, int& b). It swaps two values of the actual parameters.

void my_swap(int& a, int& b) { int temp; temp = a; a = b; b = temp; }

Implement a function void root(double a, double b, double c, double& x1, double& x2) which assigns two solutions of quadratic equation ax^2 + bx + c = 0 to variables x1 and x2.

void root(double a, double b, double c, double& x1, double& x2) { double d = b*b - 4.0 * a * c; if(d<0) { cout << "no real roots" << endl; } elseif (d==0) { x1 = -b/(2.0*a); x2 = x1; } elseif (d>0) { x1 = (-b + sqrt(d))/(2.0*a); x2 = (-b - sqrt(d))/(2.0*a); } }

Implement a function: double root(double a, double b, double c) which returns the quadratic formula.

#include <iostream> #include <cmath> using namespace std; doubleroot(double a, double b, double c) { double root1=0; double d = b*b - 4.0 * a * c; if(d < 0) { cout << "no real roots" << endl; } elseif(d == 0) { root1 = -b/(2.0*a); } elseif(d > 0) { root1 = (-b + sqrt(d))/(2.0*a); } return root1; }

Write a stub for function double totalPrice(double single_price, int total_items)

#include <iostream> using namespace std; double totalPrice(double single_price, int total_items) { return single_price*total_items) } int main( ) { double price, total_items; cout << "Enter the item price: "; cin >> price; cout << "Enter the number of items: "; cin >> total_items; cout << "Total cost: " << totalPrice(price, total_items) << endl; return 0; } Output: Enter the item price: 5.5 Enter the number of items: 10

Write an if statement to halt to program if the program fails to open a file. Assume the file to be opened has name stats.dat.

inStream.open("stats.dat"); if(inStream.fail()) { exit(1); }

Write a void function definition for a function called zero_both that has 2 reference parameters, both of which are variables of type int, and sets the values of both variables to 0.

void zeroBoth(int& a, int& b) { a = 0; b = 0; }