What is the function of the 'main' function in a C++ program?

The 'main' function in a C++ program serves as the entry point for execution. When a C++ program is run, the operating system looks for the 'main' function to begin executing the code. This function is where the program starts, and it is essential for establishing the program's flow.

The 'main' function can return an integer value, typically indicating the success or failure of the program to the operating system. In this sense, it acts as a point of initiation and termination for program execution.

The other options do not accurately describe the primary function of 'main'. While user interfaces can be created within a C++ program, the 'main' function itself does not define them. Global variables can be declared outside of 'main,' but 'main' is not specifically responsible for storing them. Additionally, while error handling can occur within 'main' or in functions called by it, this is not its primary purpose.