While loop ends prematurely

Question

I am trying out "while" loop while reading C++ tutorial. Surprisingly the below loop always exits on 2nd iteration despite I gave negative integers.

while(int sz = get_size() && sz <= 0) ;

Below is the get_size() used.

int get_size() {
  int a = 0;
  cin >> a;
  return a;
}

Answer 1

Your problem is that the statement is equivalent to

while(int sz = (get_size() && sz <= 0)) ;

Which would be undefined behavior for the first iteration because sz is uninitalized.
A solution for this would be moving the declaration outside of the loop.

int sz;
while((sz = get_size()) && sz <= 0) ;