why the last cout has no output?

Question

The fourth cout in program below has no output while the three other do. And if you remove the first command (int i =1) just the first cout has output. Please reply if you know why.

int i = 1;

int *p1;
cout <<"1. "<< p1 <<" "<< *p1 << endl;
*p1 = 1;
cout <<"2. "<< p1 <<" "<< *p1 << endl;

int *p2;
cout <<"3. "<< p2 <<" "<< *p2 << endl;
*p2 = 1;
cout <<"4. "<< p2 <<" "<< *p2 << endl;

the same code in playground👇

https://code.sololearn.com/cy8yoFGO0NFq/?ref=app

Answer 1

dare say kurwius is correct. If you set int *p2 = p1; the code runs correctly