Which header file must be included to use the string class in C++?<iostream><string><cstring><stdlib.h>

To use the string class in C++, you need to include the <string> header file. This header file provides the necessary declarations for using the std::string class, which is part of the C++ Standard Library.

Here’s a brief explanation of each option provided:

1. <iostream>: This header file is used for input and output stream operations but does not include the string class.

2. <string>: This file includes the definitions and functionalities for the std::string class, allowing for the manipulation of text in a more convenient way compared to character arrays.

3. <cstring>: This is used for C-style string handling (character arrays) and does not support the C++ std::string class.

4. <stdlib.h>: This header contains functions for memory allocation, process control, conversions, and others, but it does not relate to the string class.

Final Answer

The correct header file to include for the string class in C++ is <string>.