null_pointer.cpp

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#include <iostream>
using namespace std;
 
 
int main()
{
    int x = 0;
    int * dangling_ptr;
 
 
    cout << *dangling_ptr << endl;      // this is unpredictable & dangerous!
 
 
    int * ptr = nullptr;           // initialize a ptr to 0
 
    // cout << *ptr << endl;       // this will crash the program!
 
    // to be safe, check if the pointer is null
    // or not before using it
    if (ptr != nullptr)
        cout << "1: " << *ptr << endl;
 
 
    ptr = &x;
 
    if (ptr != nullptr)
        cout << "2: " << *ptr << endl;
 
    return 0;
}