Getting segmentation fault with c++ pointers -

so i'm trying familiarise myself c++ pointers running following code.

#include <iostream>  using namespace std;  int main(void){     int* x;     cout << &x << endl;     return 0;  } 

which works fine , prints pointer value of x but

#include <iostream>  using namespace std;  int main(void){     int* x;     *x = 100;     cout << &x << endl;     return 0;  } 

gives me segmentation fault when try tun it. why this? don't see how line should change address of x.

and prints pointer value of x but

not exactly.

• std::cout << &x; prints x's address (the pointer's address);
• std::cout << x; prints address, x points to;
• std::cout << *x; prints x points to;

---

int* x; *x = 100; 

here, x pointer, need allocate memory 100. example

int* x = new int; *x = 100; std::cout << *x; 

or just

int* x = new int( 100 ); std::cout << *x; 

without allocating memory , leaving x uninitialized, *x = 100 you're trying change random memory, leads undefined behavior.