CPP File Handling & Standard Template Library (STL)

Question 1

Which header file is required for file handling in C++?

Accepted Answer

Answer

The `<fstream>` header file in C++ provides classes for file stream operations, including `ifstream` for input from files, `ofstream` for output to files, and `fstream` for both. It is essential for performing various file I/O operations in C++.

Question 2

Which stream is used to write to a file?

Accepted Answer

ofstream

Answer

`ofstream` (output file stream) is the class specifically designed for writing data to files in C++. You create an `ofstream` object, associate it with a file, and then use stream insertion operators (`<<`) to write data to that file.

Question 3

Which STL container stores key-value pairs?

Accepted Answer

map

Answer

The `std::map` container in the C++ Standard Template Library (STL) stores elements as key-value pairs, where each key is unique and associated with a specific value. It provides efficient lookup, insertion, and deletion operations based on the keys, maintaining sorted order.

Question 4

Which operation checks if a file stream opened successfully?

Accepted Answer

file.is_open()

Answer

The `is_open()` member function of file stream objects (like `ifstream`, `ofstream`, `fstream`) is used to check if the file stream successfully opened a file. It returns `true` if the file is open and ready for I/O operations, and `false` otherwise, allowing for error handling.

Question 5

Which STL container allows access in constant time using indices?

Accepted Answer

vector

Answer

`std::vector` is a dynamic array in the C++ STL that provides constant-time (O(1)) access to its elements using their integer indices. This efficiency is due to elements being stored contiguously in memory, allowing direct calculation of an element's address.

(CPP) C++ Programming Professional Certificate Practice Test

(CPP) C++ Programming Professional Certificate Practice Test

CPP File Handling & Standard Template Library (STL)