Customer Iterator implementation

Author: sonugiri1043

Custom_Iterator.cpp

@@ -0,0 +1,30 @@
+/* 
+   Compile using 'g++ Custom_Iterator.cpp -o Custom_Iterator --std=c++11'
+*/
+
+#include "Custom_Iterator.h"
+
+using custom_iterator::vector;
+
+int main() {
+  vector< int > myVector;
+  myVector.push_back( 10 );
+  myVector.push_back( 20 );
+  myVector.push_back( 30 );
+
+  for( int i = 0; i < myVector.size(); i++ ) {
+    cout << myVector[ i ] << endl;
+  }
+
+  vector<int>::iterator iter;
+  for( iter = myVector.begin(); iter != myVector.end(); ++iter ) {
+    *iter += 20;
+    cout << *iter << endl;
+  }
+  
+  for( iter = myVector.rbegin(); iter != myVector.rend(); --iter ) {
+    *iter -= 20;
+    cout << *iter << endl;
+  } 
+  return 0;
+}

Custom_Iterator.h

@@ -0,0 +1,112 @@
+#include <iostream>
+
+using std::cout;
+using std::endl;
+
+namespace custom_iterator {
+
+  template< typename T > class vector {
+  public:
+    vector() {
+      size_ = 0;
+      capacity = CAPACITY;
+      data = new T[ capacity ];
+    }
+
+    ~vector() {
+      delete [] data;
+      data = NULL;
+      size_ = 0;
+    }
+
+    /* iterator class */
+    class iterator {
+    public:
+      iterator() {}
+
+      iterator( T *ptr ) {
+	current = ptr;
+      }
+
+      /* overload != operator */
+      bool operator!=( const iterator &rhs ) {
+	return this->current != rhs.current;
+      }
+
+      /* overload prefix ++ operator */
+      iterator& operator++() {
+	++current;
+	return *this;
+      }
+
+      /* overload prefix -- operator */
+      iterator& operator--() {
+	--current;
+	return *this;
+      }
+
+      /* overload * (de-reference) operator */
+      T& operator*() {
+	return *current;
+      }
+
+    private:
+      T *current;
+    }; /* iterator class ends here */
+
+    iterator begin() const {
+      return iterator( data );
+    }
+    
+    iterator end() const {
+      return iterator( data + size_ );
+    }
+
+    /* reverse begin */
+    iterator rbegin() const {
+      return iterator( data + size_ - 1 );
+    }
+    
+    /* reverse end */
+    iterator rend() const {
+      return iterator( data - 1 );
+    }
+
+    int size() {
+      return size_;
+    }
+    
+    void push_back( const T &value ) {
+      if( size_ == capacity )
+	expand();
+      data[ size_ ] = value;
+      size_++;
+    }
+
+    const T& operator[]( int pos ) const {
+      return data[ pos ];
+    }
+
+    T& operator[]( int pos ) {
+      return data[ pos ];
+    }
+  private:
+    void expand();
+    const int CAPACITY = 16;
+    unsigned int size_;
+    unsigned int capacity;
+    T *data;
+  };
+
+  template<typename T>
+    void vector<T>::expand() {
+    capacity += CAPACITY;
+    T *newData = new T[ capacity ];
+    for( int i = 0; i < size_; i++ ) {
+      newData[ i ] = data[ i ];
+    }
+    delete [] data;
+    data = newData;
+  }
+
+} // namespace custom_iterator ends