Question

Here is the code:

#include<iostream>

struct element{
    char *ch;
    int j;
    element* next;
};

int main(){
   char x='a';
   element*e = new element;
   e->ch= &x; 
   std::cout<<e->ch; // cout can print char* , in this case I think it's printing 4 bytes dereferenced 
}

am I seeing some undefined behavior? 0_o. Can anyone help me what’s going on?

Answer 1

You have to dereference the pointer to print the single char: std::cout << *e->ch << std::endl

Otherwise you are invoking the << overload for char *, which does something entirely different (it expects a pointer to a null-terminated array of characters).

Edit: In answer to your question about UB: The output operation performs an invalid pointer dereferencing (by assuming that e->ch points to a longer array of characters), which triggers the undefined behaviour.