Which of the following functions can be used to check if a stack is empty in C++?empty()size()top()pop()

To determine which function can be used to check if a stack is empty in C++, we need to analyze each of the provided functions:

1. empty(): This function checks whether the stack has no elements. It returns true if the stack is empty and false otherwise. Therefore, this is the correct function to check if a stack is empty.

2. size(): This function returns the number of elements in the stack. While it can be used indirectly to check if the stack is empty (by checking if size() == 0), it is not specifically designed for that purpose.

3. top(): This function returns the top element of the stack. It does not check for emptiness and should not be used for that purpose, as calling it on an empty stack would result in undefined behavior.

4. pop(): This function removes the top element of the stack. It also does not check for emptiness and could lead to undefined behavior if the stack is empty.

Conclusion

The function that should be used to check if a stack is empty in C++ is empty().