What is the purpose of a stack in C++?

In C++, a stack is a data structure used to store data that follows the principle of “Last-In-First-Out” (LIFO). The stack is utilized during program execution to store temporary variables, function calls and return addresses, local variables, and other data.

Specifically, the stack mainly has the following functions:

1. Storing temporary variables: During program execution, some variables need to be temporarily stored, and they are stored in the stack. When a function is called, the function’s parameters, return values, and local variables are all placed in the stack. And once the function is done executing, these variables are automatically released.
2. Storing function calls and return addresses: During a function call, the address of the current function is saved in the stack so that after the function is executed, it can return to the location where it was called from. This ensures the proper flow of the program’s execution.
3. Local variables are stored in the stack within a function. When a function is called, memory space is allocated for local variables, and once the function is finished executing, these variables are automatically released. This helps prevent memory leaks and variable conflicts.
4. Implementing recursion: Recursion is a technique where a function calls itself. The last-in-first-out (LIFO) property of the stack makes it very suitable for implementing recursion. Each time the function is called recursively, its parameters and local variables are stored in the stack, and when the recursion ends, these variables are released in the reverse order.

In a nutshell, stacks in C++ play a role in temporarily storing data, function call and return addresses, local variables, etc., making the execution flow of a program clearer and more orderly.