File Handling & Standard Template Library (STL) Flashcards
7 cards from real CPP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 File Handling & Standard Template Library (STL) flashcards as text
What happens when you write to a std::ofstream that was opened with std::ios::binary?
Answer: No newline translation is performed
Binary mode suppresses platform-specific newline translation (e.g., '\n' is not converted to '\r\n' on Windows).
Which STL container provides constant-time access by index and automatic resizing?
Answer: std::vector
std::vector stores elements contiguously and supports O(1) random access via operator[], resizing as needed.
What does std::copy_if() do compared to std::copy()?
Answer: Only copies elements satisfying a predicate
std::copy_if applies a predicate and copies only elements for which it returns true.
Which method must you call before reusing a stream object after a failure?
Answer: clear()
clear() resets all error state flags (failbit, eofbit, badbit) so the stream can be used again.
What is the invalidation rule for std::vector iterators after push_back()?
Answer: All iterators are invalidated if reallocation occurs
If push_back() triggers a reallocation (capacity exceeded), all existing iterators, pointers, and references are invalidated.
Which STL function object compares two values using operator>?
Answer: std::greater
std::greater is a function object that returns true when its first argument is greater than the second.
Which method of std::map returns an iterator to an element if found, or end() if not?
Answer: find()
find() searches for a key and returns an iterator to it, or end() if the key is absent.