- Example 1 (Quadratic equation)
/**
* QuadraticEquation - Solves a quadratic equation
* Author: Humberto Silva Naves
* PIC 10A - 10/16/2012
*/
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double a, b, c;
double delta;
// Get the coefficients
cout << "What are the coefficients of the quadratic equation ax^2 + bx + c = 0? ";
cin >> a >> b >> c;
// Compute the delta
delta = b * b - 4 * a * c;
if (delta < 0) { // If delta is negative, the equation has no real roots
cout << "The equation has no real roots!" << endl;
} else if (fabs(delta) < 1e-7) { // Root of multiplicity 2
double root = -b / (2 * a);
cout << "The equation has only one root: " << root << endl;
} else { // 2 roots
double sqrtdelta = sqrt (delta);
double root1 = (-b - sqrtdelta) / (2 * a);
double root2 = (-b + sqrtdelta) / (2 * a);
cout << "The equation has two roots: " << root1 << ", " << root2 << endl;
}
return 0;
}
- Example 2 (First and last names)
/**
* FirstName - Prints out first and last names, given full name
* Author: Humberto Silva Naves
* PIC 10A - 10/16/2012
*/
#include <iostream>
using namespace std;
int main()
{
string fullname;
cout << "Full name: ";
getline (cin, fullname);
int separator;
separator = fullname.find(" ");
string firstname = fullname.substr (0, separator);
string lastname = fullname.substr (separator + 1);
cout << "First Name: " << firstname << endl;
cout << "Last Name: " << lastname << endl;
return 0;
}
- Example 3 (English article)
/**
* EnglishArticle - Prepends a word with an indefinite article
* Author: Humberto Silva Naves
* PIC 10A - 10/16/12
*/
#include <iostream>
using namespace std;
int main()
{
string word;
cout << "Give me a word and I will prepend an article to it: ";
cin >> word;
// Get the first letter of the word
string firstletter = word.substr (0, 1);
bool vowel = false;
// Check if first letter is a vowel
if (firstletter == "a") vowel = true;
else if (firstletter == "e") vowel = true;
else if (firstletter == "i") vowel = true;
else if (firstletter == "o") vowel = true;
else if (firstletter == "u") vowel = true;
if (vowel) cout << "an " << word << endl;
else cout << "a " << word << endl;
return 0;
}
- Example 4 (Numberts to english)
/**
* NumbersToEnglish - Convert number into English words.
* Author: Humberto Silva Naves
* PIC 10A - 10/16/2012
*/
#include <iostream>
using namespace std;
int main()
{
int n, digit1, digit2;
cout << "Give me a number: ";
cin >> n;
if (n >= 100) {
cout << "Number too big!";
n = 0;
} else if (n == 0) {
cout << "zero" << endl;
} else if (n >= 10) {
if (n < 20) {
if (n == 10) cout << "ten";
else if (n == 11) cout << "eleven";
else if (n == 12) cout << "twelve";
else if (n == 13) cout << "thirteen";
else if (n == 14) cout << "fourteen";
else if (n == 15) cout << "fifteen";
else if (n == 16) cout << "sixteen";
else if (n == 17) cout << "seventeen";
else if (n == 18) cout << "eighteen";
else cout << "nineteen";
} else {
int digit1 = (n / 10) % 10;
if (digit1 == 2) cout << "twenty";
else if (digit1 == 3) cout << "thirty";
else if (digit1 == 4) cout << "fourty";
else if (digit1 == 5) cout << "fifty";
else if (digit1 == 6) cout << "sixty";
else if (digit1 == 7) cout << "seventy";
else if (digit1 == 8) cout << "eighty";
else cout << "ninety";
n = n % 10;
cout << " ";
}
}
if (n == 1) cout << "one";
else if (n == 2) cout << "two";
else if (n == 3) cout << "three";
else if (n == 4) cout << "four";
else if (n == 5) cout << "five";
else if (n == 6) cout << "six";
else if (n == 7) cout << "seven";
else if (n == 8) cout << "eight";
else if (n == 9) cout << "nine";
cout << endl;
return 0;
}
- Example 5 (Recursive factorial)
/**
* RecursiveFactorial - Computes the factorial of a number
* Author: Humberto Silva Naves
* PIC 10A - 10/30/2012
*/
#include <iostream>
using namespace std;
// Recursive implementation of factorial
int factorial(int n)
{
if (n == 0) return 1; // the base case
return n * factorial(n - 1);
}
int main()
{
int n;
cout << "Please type a number: ";
cin >> n;
cout << n << "! = " << factorial(n) << endl;
return 0;
}
- Example 6 (Recursive fibonacci)
/**
* RecursiveFibonacci - Computes the n-th fibonacci number
* Author: Humberto Silva Naves
* PIC 10A - 10/30/2012
*/
#include <iostream>
using namespace std;
// Recursive function to compute the n-th fibonacci number
int fibonacci(int n)
{
if (n == 1 || n == 2) return 1;
return fibonacci(n - 1) + fibonacci(n - 2);
}
int main()
{
int n;
cout << "Please type a number: ";
cin >> n;
cout << "the " << n << "-th fibonacci number is " << fibonacci(n) << endl;
return 0;
}
- Example 7 (Fibonacci)
/**
* Fibonacci - Computes the n-th fibonacci number
* Author: Humberto Silva Naves
* PIC 10A - 10/30/2012
*/
#include <iostream>
using namespace std;
// Iterative function to compute the n-th fibonacci number
int fibonacci(int n)
{
int i, fib, fib2;
fib = fib2 = 1;
if (n == 1 || n == 2) return 1;
for (i = 3; i <= n; i++) {
int temp = fib2;
fib2 = fib;
fib = fib + temp;
}
return fib;
}
int main()
{
int n;
cout << "Please type a number: ";
cin >> n;
cout << "the " << n << "-th fibonacci number is " << fibonacci(n) << endl;
return 0;
}
- Example 8 (Hanoi towers)
/**
* HanoiTowers - Solves the hanoi towers problem
* Author: Humberto Silva Naves
* PIC 10A - 10/30/2012
*/
#include <iostream>
using namespace std;
int solve_hanoi(int n, int origin, int goal, int auxiliary)
{
if (n == 1) {
cout << origin << " -> " << goal << endl;
} else {
solve_hanoi(n - 1, origin, auxiliary, goal);
cout << origin << " -> " << goal << endl;
solve_hanoi(n - 1, auxiliary, goal, origin);
}
}
int main()
{
int n;
cout << "Please type a number: ";
cin >> n;
cout << "The solution of the hanoi towers problem is:" << endl;
solve_hanoi(n, 1, 3, 2);
return 0;
}
- Example 9 (Phonebook)
#include <iostream>
#include <string>
#include <vector>
using namespace std;
class Contact
{
private:
string name;
string phone;
public:
Contact(string cName, string cPhone);
string get_name() const;
string get_phone() const;
void print_contact() const;
};
class Phonebook
{
private:
vector<Contact> entries;
public:
Phonebook();
void add_contact(Contact c);
Contact find_contact(string name) const;
};
Contact::Contact(string cName, string cPhone)
{
name = cName;
phone = cPhone;
}
string Contact::get_name() const
{
return name;
}
string Contact::get_phone() const
{
return phone;
}
void Contact::print_contact() const
{
cout << "Name: " << name << endl;
cout << "Phone: " << phone << endl;
}
Phonebook::Phonebook()
{
}
void Phonebook::add_contact(Contact c)
{
entries.push_back(c);
}
Contact Phonebook::find_contact(string name) const
{
for(int i = 0; i < entries.size(); i++) {
Contact c = entries[i];
if (c.get_name() == name) {
return c;
}
}
return Contact("NONE", "NONE");
}
int main()
{
string cmd;
string name, phone;
Phonebook book;
cout << "Phonebook v1.0" << endl;
do {
cout << ">";
getline(cin, cmd);
if (cmd == "ADD") {
cout << "Name? ";
getline(cin, name);
cout << "Phone? ";
getline(cin, phone);
book.add_contact(Contact(name, phone));
} else if (cmd == "FIND") {
cout << "Name? ";
getline(cin, name);
Contact c = book.find_contact(name);
c.print_contact();
} else if (cmd != "DONE") {
cout << "Invalid command: " << cmd << endl;
}
} while (cmd != "DONE");
return 0;
}
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