Pointer Basics
A pointer is a variable that stores the memory address of another variable. Pointers are fundamental to C++ and enable dynamic memory, data structures, and efficient code.
Example
int value = 42;
int* ptr = &value; // ptr holds the address of value
cout << value << endl; // 42 (the value)
cout << &value << endl; // 0x7fff... (address of value)
cout << ptr << endl; // same address
cout << *ptr << endl; // 42 (dereference — get value at address)
// Modify through pointer
*ptr = 100;
cout << value << endl; // 100
// Null pointer
int* empty = nullptr; // points to nothing
if (empty == nullptr) {
cout << "Pointer is null" << endl;
}Dynamic Memory
Use new to allocate memory on the heap and delete to free it. For modern C++, prefer smart pointers.
Example
// Dynamic allocation
int* num = new int(42);
cout << *num << endl; // 42
delete num; // free memory
// Dynamic array
int* arr = new int[5]{10, 20, 30, 40, 50};
cout << arr[2] << endl; // 30
delete[] arr; // free array memory
// Smart pointers (C++11) — automatic memory management
#include <memory>
unique_ptr<int> uptr = make_unique<int>(42);
cout << *uptr << endl; // 42
// No need to delete — freed automatically
shared_ptr<int> sptr = make_shared<int>(100);
cout << *sptr << endl; // 100