Basic concept and application of stack?

Answer 1

A stack is a last in first out (LIFO) data structure. Stacks are typically used in backtracking algorithms where values are popped off the stack in the reverse order they were pushed onto the stack. Procedural programming languages make use of a call stack so that functions can easily return control to their callers -- which is vital when a function may have more than one call site. The calling function pushes the return address onto the call stack and then passes control to the callee function. When the callee has finished its task, the return address is popped off the stack and control returned to that address. In this way, functions can call other functions (including themselves) without losing track of where those calls came from. The call stack is also used to store a function's local variables as well as any arguments that were passed to the function by its caller. The function's exception handlers can also be placed on the stack. When an unhandled exception occurs, the call stack unwinds until a stack frame with a suitable exception handler is located. If the call stack unwinds all the way to the program's entry point (the main function) and there is still no handler, the program terminates with an unhandled exception error.