C++ Programming Code Examples

/* Program to Implement Fibonacci Heap */ #include <iostream> #include <cmath> #include <cstdlib> using namespace std; /* Node Declaration */ struct node { int n; int degree; node* parent; node* child; node* left; node* right; char mark; char C; }; /* Class Declaration */ class FibonacciHeap { private: int nH; node *H; public: node* InitializeHeap(); int Fibonnaci_link(node*, node*, node*); node *Create_node(int); node *Insert(node *, node *); node *Union(node *, node *); node *Extract_Min(node *); int Consolidate(node *); int Display(node *); node *Find(node *, int); int Decrease_key(node *, int, int); int Delete_key(node *,int); int Cut(node *, node *, node *); int Cascase_cut(node *, node *); FibonacciHeap() { H = InitializeHeap(); } }; /* Initialize Heap */ node* FibonacciHeap::InitializeHeap() { node* np; np = NULL; return np; } /* Create Node */ node* FibonacciHeap::Create_node(int value) { node* x = new node; x->n = value; return x; } /* Insert Node */ node* FibonacciHeap::Insert(node* H, node* x) { x->degree = 0; x->parent = NULL; x->child = NULL; x->left = x; x->right = x; x->mark = 'F'; x->C = 'N'; if (H != NULL) { (H->left)->right = x; x->right = H; x->left = H->left; H->left = x; if (x->n < H->n) H = x; } else { H = x; } nH = nH + 1; return H; } /* Link Nodes in Fibonnaci Heap */ int FibonacciHeap::Fibonnaci_link(node* H1, node* y, node* z) { (y->left)->right = y->right; (y->right)->left = y->left; if (z->right == z) H1 = z; y->left = y; y->right = y; y->parent = z; if (z->child == NULL) z->child = y; y->right = z->child; y->left = (z->child)->left; ((z->child)->left)->right = y; (z->child)->left = y; if (y->n < (z->child)->n) z->child = y; z->degree++; } /* Union Nodes in Fibonnaci Heap */ node* FibonacciHeap::Union(node* H1, node* H2) { node* np; node* H = InitializeHeap(); H = H1; (H->left)->right = H2; (H2->left)->right = H; np = H->left; H->left = H2->left; H2->left = np; return H; } /* Display Fibonnaci Heap */ int FibonacciHeap::Display(node* H) { node* p = H; if (p == NULL) { cout<<"The Heap is Empty"<<endl; return 0; } cout<<"The root nodes of Heap are: "<<endl; do { cout<<p->n; p = p->right; if (p != H) { cout<<"-->"; } } while (p != H && p->right != NULL); cout<<endl; } /* Extract Min Node in Fibonnaci Heap */ node* FibonacciHeap::Extract_Min(node* H1) { node* p; node* ptr; node* z = H1; p = z; ptr = z; if (z == NULL) return z; node* x; node* np; x = NULL; if (z->child != NULL) x = z->child; if (x != NULL) { ptr = x; do { np = x->right; (H1->left)->right = x; x->right = H1; x->left = H1->left; H1->left = x; if (x->n < H1->n) H1 = x; x->parent = NULL; x = np; } while (np != ptr); } (z->left)->right = z->right; (z->right)->left = z->left; H1 = z->right; if (z == z->right && z->child == NULL) H = NULL; else { H1 = z->right; Consolidate(H1); } nH = nH - 1; return p; } /* Consolidate Node in Fibonnaci Heap */ int FibonacciHeap::Consolidate(node* H1) { int d, i; float f = (log(nH)) / (log(2)); int D = f; node* A[D]; for (i = 0; i <= D; i++) A[i] = NULL; node* x = H1; node* y; node* np; node* pt = x; do { pt = pt->right; d = x->degree; while (A[d] != NULL) { y = A[d]; if (x->n > y->n) { np = x; x = y; y = np; } if (y == H1) H1 = x; Fibonnaci_link(H1, y, x); if (x->right == x) H1 = x; A[d] = NULL; d = d + 1; } A[d] = x; x = x->right; } while (x != H1); H = NULL; for (int j = 0; j <= D; j++) { if (A[j] != NULL) { A[j]->left = A[j]; A[j]->right =A[j]; if (H != NULL) { (H->left)->right = A[j]; A[j]->right = H; A[j]->left = H->left; H->left = A[j]; if (A[j]->n < H->n) H = A[j]; } else { H = A[j]; } if(H == NULL) H = A[j]; else if (A[j]->n < H->n) H = A[j]; } } } /* Decrease key of Nodes in Fibonnaci Heap */ int FibonacciHeap::Decrease_key(node*H1, int x, int k) { node* y; if (H1 == NULL) { cout<<"The Heap is Empty"<<endl; return 0; } node* ptr = Find(H1, x); if (ptr == NULL) { cout<<"Node not found in the Heap"<<endl; return 1; } if (ptr->n < k) { cout<<"Entered key greater than current key"<<endl; return 0; } ptr->n = k; y = ptr->parent; if (y != NULL && ptr->n < y->n) { Cut(H1, ptr, y); Cascase_cut(H1, y); } if (ptr->n < H->n) H = ptr; return 0; } /* Cut Nodes in Fibonnaci Heap */ int FibonacciHeap::Cut(node* H1, node* x, node* y) { if (x == x->right) y->child = NULL; (x->left)->right = x->right; (x->right)->left = x->left; if (x == y->child) y->child = x->right; y->degree = y->degree - 1; x->right = x; x->left = x; (H1->left)->right = x; x->right = H1; x->left = H1->left; H1->left = x; x->parent = NULL; x->mark = 'F'; } /* Cascade Cutting in Fibonnaci Heap */ int FibonacciHeap::Cascase_cut(node* H1, node* y) { node* z = y->parent; if (z != NULL) { if (y->mark == 'F') { y->mark = 'T'; } else { Cut(H1, y, z); Cascase_cut(H1, z); } } } /* Find Nodes in Fibonnaci Heap */ node* FibonacciHeap::Find(node* H, int k) { node* x = H; x->C = 'Y'; node* p = NULL; if (x->n == k) { p = x; x->C = 'N'; return p; } if (p == NULL) { if (x->child != NULL ) p = Find(x->child, k); if ((x->right)->C != 'Y' ) p = Find(x->right, k); } x->C = 'N'; return p; } /* Delete Nodes in Fibonnaci Heap */ int FibonacciHeap::Delete_key(node* H1, int k) { node* np = NULL; int t; t = Decrease_key(H1, k, -5000); if (!t) np = Extract_Min(H); if (np != NULL) cout<<"Key Deleted"<<endl; else cout<<"Key not Deleted"<<endl; return 0; } /* Main Contains Menu */ int main() { int n, m, l; FibonacciHeap fh; node* p; node* H; H = fh.InitializeHeap(); while (1) { cout<<"----------------------------"<<endl; cout<<"Operations on Binomial heap"<<endl; cout<<"----------------------------"<<endl; cout<<"1)Insert Element in the heap"<<endl; cout<<"2)Extract Minimum key node"<<endl; cout<<"3)Decrease key of a node"<<endl; cout<<"4)Delete a node"<<endl; cout<<"5)Display Heap"<<endl; cout<<"6)Exit"<<endl; cout<<"Enter Your Choice: "; cin>>l; switch(l) { case 1: cout<<"Enter the element to be inserted: "; cin>>m; p = fh.Create_node(m); H = fh.Insert(H, p); break; case 2: p = fh.Extract_Min(H); if (p != NULL) cout<<"The node with minimum key: "<<p->n<<endl; else cout<<"Heap is empty"<<endl; break; case 3: cout<<"Enter the key to be decreased: "; cin>>m; cout<<"Enter new key value: "; cin>>l; fh.Decrease_key(H, m, l); break; case 4: cout<<"Enter the key to be deleted: "; cin>>m; fh.Delete_key(H, m); break; case 5: cout<<"The Heap is: "<<endl; fh.Display(H); break; case 6: exit(1); default: cout<<"Wrong Choice"<<endl; } } return 0; }

/* log() function is an inbuilt function in C++ STL, which is defined in <complex> header file. log() returns complex natural logarithmic value of a complex value. The difference between the log() in math header file and log() of complex header file is that it is used to calculate the complex logarithmic where log() of math header file calculates normal logarithmic value. */ /* Compute natural logarithm by log() function code example */ #include <iostream> #include <cmath> using namespace std; int main () { double x = 13.056, result; result = log (x); cout << "log(x) = " << result << endl; x = -3.591; result = log (x); cout << "log(x) = " << result << endl; return 0; }

/* using public and private in C++ Class */ // Program to illustrate the working of // public and private in C++ Class #include <iostream> using namespace std; class Room { private: double length; double breadth; double height; public: // function to initialize private variables void initData(double len, double brth, double hgt) { length = len; breadth = brth; height = hgt; } double calculateArea() { return length * breadth; } double calculateVolume() { return length * breadth * height; } }; int main() { // create object of Room class Room room1; // pass the values of private variables as arguments room1.initData(42.5, 30.8, 19.2); cout << "Area of Room = " << room1.calculateArea() << endl; cout << "Volume of Room = " << room1.calculateVolume() << endl; return 0; }

/* std::min is defined in the header file <algorithm> and is used to find out the smallest of the number passed to it. It returns the first of them, if there are more than one. */ /* accept two values and return the smaller one by min() function code example. */ #include <iostream> #include <algorithm> using namespace std; // Defining the binary function bool comp(int a, int b) { return (a < b); } int main() { int a = 5; int b = 7; cout << std::min(a, b, comp) << "\n"; // Returns the first one if both the numbers // are same cout << std::min(7, 7, comp); return 0; }

/* using #include directive in C language */ #include <stdio.h> int main() { /* * C standard library printf function * defined in the stdio.h header file */ printf("I love you Clementine"); printf("I love you so much"); printf("HappyCodings"); return 0; }

/* While Loop Statement in C++ language */ // program to find the sum of positive numbers // if the user enters a negative number, the loop ends // the negative number entered is not added to the sum #include <iostream> using namespace std; int main() { int number; int sum = 0; // take input from the user cout << "Enter a number: "; cin >> number; while (number >= 0) { // add all positive numbers sum += number; // take input again if the number is positive cout << "Enter a number: "; cin >> number; } // display the sum cout << "\nThe sum is " << sum << endl; return 0; }

/* break statement with while loop code example */ // program to find the sum of positive numbers // if the user enters a negative numbers, break ends the loop // the negative number entered is not added to sum #include <iostream> using namespace std; int main() { int number; int sum = 0; while (true) { // take input from the user cout << "Enter a number: "; cin >> number; // break condition if (number < 0) { break; } // add all positive numbers sum += number; } // display the sum cout << "The sum is " << sum << endl; return 0; }

/* Structure is a collection of variables of different data types under a single name. It is similar to a class in that, both holds a collecion of data of different data types. */ #include <iostream> using namespace std; struct Person { char name[50]; int age; float salary; }; int main() { Person p1; cout << "Enter Full name: "; cin.get(p1.name, 50); cout << "Enter age: "; cin >> p1.age; cout << "Enter salary: "; cin >> p1.salary; cout << "\nDisplaying Information." << endl; cout << "Name: " << p1.name << endl; cout <<"Age: " << p1.age << endl; cout << "Salary: " << p1.salary; return 0; }

/* write a C program which demonstrate use of if-else-if ladder statement */ /* Program to Print Day Names using Else If Ladder in C++*/ #include <iostream> using namespace std; int main() { int day; cout << "Enter Day Number: "; cin >> day; cout << "Day is "; if (day == 1) cout << "Sunday" << endl; else if (day == 2) cout << "Monday" << endl; else if (day == 3) cout << "Tuesday" << endl; else if (day == 4) cout << "Wednesday" << endl; else if (day == 5) cout << "Thursday" << endl; else if (day == 6) cout << "Friday" << endl; else cout << "Saturday" << endl; return 0; }

/* namespaces in C++ language */ // A C++ code to demonstrate that we can define // methods outside namespace. #include <iostream> using namespace std; // Creating a namespace namespace ns { void display(); class happy { public: void display(); }; } // Defining methods of namespace void ns::happy::display() { cout << "ns::happy::display()\n"; } void ns::display() { cout << "ns::display()\n"; } // Driver code int main() { ns::happy obj; ns::display(); obj.display(); return 0; }

/* terminate the process normally, performing the regular cleanup for terminating programs by exit() function code example */ #include<iostream> using namespace std; int main() { int i; cout<<"Enter a non-zero value: "; //user input cin>>i; if(i) // checks whether the user input is non-zero or not { cout<<"Valid input.\n"; } else { cout<<"ERROR!"; //the program exists if the value is 0 exit(0); } cout<<"The input was : "<<i; }

/* the switch statement helps in testing the equality of a variable against a set of values */ #include <iostream> using namespace std; int main () { // local variable declaration: char grade = 'D'; switch(grade) { case 'A' : cout << "Excellent!" << endl; break; case 'B' : case 'C' : cout << "Well done" << endl; break; case 'D' : cout << "You passed" << endl; break; case 'F' : cout << "Better try again" << endl; break; default : cout << "Invalid grade" << endl; } cout << "Your grade is " << grade << endl; return 0; }

/* Standard end line (endl) in C++ language */ //The header file iostream is imported to enable us to use cout in the program #include <iostream> //a namespace called std is defined using namespace std; //main method is called int main( ) { //cout is used to output the statement cout<< "Welcome to "; //cout is used to output the statement along with endl to start the next statement in the new line and flush the output stream cout<< "C#"<<endl; //cout is used to output the statement along with endl to start the next statement in the new line and flush the output stream cout<< "Learning is fun"<<endl; }

/* If Else Statement in C++ Language */ #include <iostream> using namespace std; int main () { // local variable declaration: int a = 100; // check the boolean condition if( a < 20 ) { // if condition is true then print the following cout << "a is less than 20;" << endl; } else { // if condition is false then print the following cout << "a is not less than 20;" << endl; } cout << "value of a is : " << a << endl; return 0; }

/* Standard Input Stream (cin) in C++ language */ // cin with Member Functions #include <iostream> using namespace std; int main() { char name[20], address[20]; cout << "Name: "; // use cin with getline() cin.getline(name, 20); cout << "Address: "; cin.getline(address, 20); cout << endl << "You entered " << endl; cout << "Name = " << name << endl; cout << "Address = " << address; return 0; }

/* simple code example by main() function in C++ */ #include <iostream> using namespace std; int main() { int day = 4; switch (day) { case 1: cout << "Monday"; break; case 2: cout << "Tuesday"; break; case 3: cout << "Wednesday"; break; case 4: cout << "Thursday"; break; case 5: cout << "Friday"; break; case 6: cout << "Saturday"; break; case 7: cout << "Sunday"; break; } return 0; }

/* standard output stream (cout) in C++ language */ #include <iostream> using namespace std; int main() { string str = "Do not interrupt me"; char ch = 'm'; // use cout with write() cout.write(str,6); cout << endl; // use cout with put() cout.put(ch); return 0; }

/* For Loop Statement in C++ Language */ // C++ program to find the sum of first n natural numbers // positive integers such as 1,2,3,...n are known as natural numbers #include <iostream> using namespace std; int main() { int num, sum; sum = 0; cout << "Enter a positive integer: "; cin >> num; for (int i = 1; i <= num; ++i) { sum += i; } cout << "Sum = " << sum << endl; return 0; }

/* A constructor is a special type of member function that is called automatically when an object is created. In C++, a constructor has the same name as that of the class and it does not have a return type. */ #include <iostream> using namespace std; // declare a class class Wall { private: double length; double height; public: // initialize variables with parameterized constructor Wall(double len, double hgt) { length = len; height = hgt; } // copy constructor with a Wall object as parameter // copies data of the obj parameter Wall(Wall &obj) { length = obj.length; height = obj.height; } double calculateArea() { return length * height; } }; int main() { // create an object of Wall class Wall wall1(10.5, 8.6); // copy contents of wall1 to wall2 Wall wall2 = wall1; // print areas of wall1 and wall2 cout << "Area of Wall 1: " << wall1.calculateArea() << endl; cout << "Area of Wall 2: " << wall2.calculateArea(); return 0; }

/* C++ allows us to allocate the memory of a variable or an array in run time. This is known as dynamic memory allocation. The new operator denotes a request for memory allocation on the Free Store. If sufficient memory is available, new operator initializes the memory and returns the address of the newly allocated and initialized memory to the pointer variable. */ /* Allocate storage space by operator new */ // C++ program code example to illustrate dynamic allocation and deallocation of memory using new and delete #include <iostream> using namespace std; int main () { // Pointer initialization to null int* p = NULL; // Request memory for the variable // using new operator p = new(nothrow) int; if (!p) cout << "allocation of memory failed\n"; else { // Store value at allocated address *p = 29; cout << "Value of p: " << *p << endl; } // Request block of memory // using new operator float *r = new float(75.25); cout << "Value of r: " << *r << endl; // Request block of memory of size n int n = 5; int *q = new(nothrow) int[n]; if (!q) cout << "allocation of memory failed\n"; else { for (int i = 0; i < n; i++) q[i] = i+1; cout << "Value store in block of memory: "; for (int i = 0; i < n; i++) cout << q[i] << " "; } // freed the allocated memory delete p; delete r; // freed the block of allocated memory delete[] q; return 0; }