Program to create Custom Vector Class in C++
The task is to implement a custom vector class similar to the STL vector with following functions:
- int push_back(data): adds an element(of any data_type) to the end of array and also returns the number of elements in that vector
- data_type pop_back(): removes an element from the end of array, also returns the popped element
- int size() const: returns the current size of vector
Below program implements a custom vector class in C++ with above mentioned functionalities:
// C++ program to implement Custom Vector// class#include "iostream"#define ll long longusing namespace std; // Template class to create vector of// different data_typetemplate <typename DT>class GenericMyVector {private: DT* arr; // Variable to store the current capacity // of the vector ll capacity; // Variable to store the length of the // vector ll length; public: explicit GenericMyVector(ll = 100); // Function that returns the number of // elements in array after pushing the data ll push_back(DT); // function that returns the popped element DT pop_back(); // Function that return the size of vector ll size() const; DT& operator[](ll); // Iterator Class class iterator { private: // Dynamic array using pointers DT* ptr; public: explicit iterator() : ptr(nullptr) { } explicit iterator(DT* p) : ptr(p) { } bool operator==(const iterator& rhs) const { return ptr == rhs.ptr; } bool operator!=(const iterator& rhs) const { return !(*this == rhs); } DT operator*() const { return *ptr; } iterator& operator++() { ++ptr; return *this; } iterator operator++(int) { iterator temp(*this); ++*this; return temp; } }; // Begin iterator iterator begin() const; // End iterator iterator end() const;}; // Template class to return the size of// vector of different data_typetemplate <typename DT>GenericMyVector<DT>::GenericMyVector(ll n) : capacity(n), arr(new DT[n]), length(0){} // Template class to insert the element// in vectortemplate <typename DT>ll GenericMyVector<DT>::push_back(DT data){ if (length == capacity) { DT* old = arr; arr = new DT[capacity = capacity * 2]; copy(old, old + length, arr); delete[] old; } arr[length++] = data; return length;} // Template class to return the popped element// in vectortemplate <typename DT>DT GenericMyVector<DT>::pop_back(){ return arr[length-- - 1];} // Template class to return the size of// vectortemplate <typename DT>ll GenericMyVector<DT>::size() const{ return length;} // Template class to return the element of// vector at given indextemplate <typename DT>DT& GenericMyVector<DT>::operator[](ll index){ // if given index is greator than the // size of vector print Error if (index >= length) { cout << "Error: Array index out of bound"; exit(0); } // else return value at that index return *(arr + index);} // Template class to return begin iteratortemplate <typename DT>typename GenericMyVector<DT>::iterator GenericMyVector<DT>::begin() const{ return iterator(arr);} // Template class to return end iteratortemplate <typename DT>typename GenericMyVector<DT>::iterator GenericMyVector<DT>::end() const{ return iterator(arr + length);} // Template class to display element in// vectortemplate <typename V>void display_vector(V& v){ // Declare iterator typename V::iterator ptr; for (ptr = v.begin(); ptr != v.end(); ptr++) { cout << *ptr << ' '; } cout << '\n';} // Driver codeint main(){ cout << "For Integer data_type" << endl; GenericMyVector<int> v; v.push_back(5); v.push_back(6); v.push_back(7); v.push_back(8); v.push_back(9); v.push_back(10); v.push_back(11); v.push_back(12); // Declare iterator for traversal in // vector v GenericMyVector<int>::iterator it; // Function called to display element in // vector in v cout << "Element in vector v : "; display_vector(v); // Print the size of vector v cout << "size: " << v.size() << endl; // Print Element at index 2 cout << "v[2]: " << v[2] << '\n'; // Pop an element and print it cout << "Popped Element: " << v.pop_back() << '\n'; display_vector(v); cout << endl; cout << "For Char data_type" << endl; GenericMyVector<char> c; c.push_back('a'); c.push_back('b'); c.push_back('c'); c.push_back('d'); c.push_back('e'); c.push_back('f'); c.push_back('g'); c.push_back('h'); // Declare iterator for traversal in // vector c GenericMyVector<char>::iterator it1; // Function called to display element in // vector in c cout << "Element in vector c : "; display_vector(c); // Print the size of vector c cout << "size: " << c.size() << '\n'; // Print Element at index 2 cout << "c[2]: " << c[2] << '\n'; // Pop an element and print it cout << "pop: " << c.pop_back() << '\n'; // Function called to display element in // vector in c cout << "Element in vector c : "; display_vector(c); return 0;} |
Output:
For Integer data_type Element in vector v : 5 6 7 8 9 10 11 12 size: 8 v[2]: 7 Popped Element: 12 5 6 7 8 9 10 11 For Char data_type Element in vector c : a b c d e f g h size: 8 c[2]: c pop: h Element in vector c : a b c d e f g
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