? 1 : 2 -> auto

What this C++ language-knowledge question tests

This is a hard C++ question that probes deep familiarity with modern language features and type deduction rules. It requires you to reason carefully about how the compiler interprets syntax that may appear ambiguous or unintuitive at first glance.

Questions of this type appear in technical interviews because they separate candidates who have only surface-level C++ knowledge from those who understand the subtle rules governing declarations, template instantiation, and operator precedence. The ability to predict compiler behaviour—without running the code—is valued in environments where code review and reasoning about code correctness matter.

• Type deduction and template argument rules
• Operator precedence and associativity
• Declaration syntax and the most-vexing parse
• Ternary and conditional operators