A recursive algorithm calls itself which usually passes the return value as a parameter to the algorithm again. This parameter is the input while the return value is the output. Recursive algorithm is a method of simplification that divides the problem into sub-problems of the same nature. The result of one recursion is the input for the next recursion. The repletion is in the self-similar fashion. The algorithm calls itself with smaller input values and obtains the results by simply performing the operations on these smaller values. Generation of factorial, Fibonacci number series are the examples of recursive algorithms.
Properties
A recursive function can go infinite like a loop. To avoid infinite running of recursive function, there are two properties that a recursive function must have −
• Base criteria − There must be at least one base criteria or condition, such that, when this condition is met the function stops calling itself recursively.
• Progressive approach − The recursive calls should progress in such a way that each time a recursive call is made it comes closer to the base criteria.
Implementation
Many programming languages implement recursion by means of stacks. Generally, whenever a function (caller) calls another function (Calle) or itself as calle, the caller function transfers execution control to the Calle. This transfer process may also involve some data to be passed from the caller to the calle.
This implies, the caller function has to suspend its execution temporarily and resume later when the execution control returns from the calle function. Here, the caller function needs to start exactly from the point of execution where it puts itself on hold. It also needs the exact same data values it was working on. For this purpose, an activation record (or stack frame) is created for the caller function.
