Lazy Filter Invocation Count

Understanding lazy evaluation and filter invocation in C++

This medium-difficulty C++ language-knowledge question tests whether you understand how lazy evaluation works in modern C++ and when lambda expressions are actually invoked during filtering operations. It's the kind of problem that reveals whether a candidate has hands-on experience with functional-style constructs or merely surface-level familiarity.

To answer correctly, you need to trace through the control flow carefully: identify which operations are eager versus lazy, understand when predicates are evaluated, and track the order of execution. The question rewards precise mental execution of the code path over guessing.

• Lazy vs. eager evaluation semantics
• Lambda capture and invocation timing
• Short-circuit evaluation in filtering chains
• Side effects and observable behaviour in functional pipelines