Recursion

RECURSION

Introduction

You can express most of the problems in the following program by using recursion. We represent the function add by using recursion.

Program

#include  int add(int pk,int pm); main() {     int k ,i,m;     m=2;     k=3;     i=add(k,m);.     printf("The value of addition is %d\n",i); } int add(int pk,int pm) {     if(pm==0) return(pk);          \\ A     else return(1+add(pk,pm-1));   \\ B } 

Explanation

1. The add function is recursive as follows:

   add (x, y) = 1 + add(x, y-1)      y > 0        = x                   y = 0 for example,     add(3, 2) = 1 + add(3, 4)     add(3, 1) = 1 + add(3, 0)     add(3, 0) = 3     add(3, 1) = 1+3 = 4     add(3, 2) = 1+4 = 5 

2. The recursive expression is 1+add(pk, pm-1). The terminating condition is pm = 0 and the recursive condition is pm > 0.