Using assignment as a condition expression?

Question

Consider:

if (a=5) {
   /* do something */
}

How does the assignment work as a condition?

Is it based on non-zero value of l-value?

user_579078 · Answer

In more modern usage, you may sometimes see this pattern used to handle optionals:

std::optional x = ...;
if (auto v = x) {
  // Block only executes if x contained a value, accessible as *v
}