Power through recursion (C++ Tutorial)

Power through recursion

powerRecursive() calculates the power of a number recursively. It takes 2 parameters; first is the base and second is the exponent.

For example,

If base is 3 and exp is 0, then this function will return 1,

If base is 3 and exp is 1, then this function will return 3,

If base is 3 and exp is 2, then this function will return 9,

If base is 3 and exp is 3, then this function will return 27,

If base is 3 and exp is 4, then this function will return 81,

If base is 3 and exp is 5, then this function will return 243,

If base is 3 and exp is 6, then this function will return 729,

If base is 3 and exp is 7, then this function will return 2187,

If base is 3 and exp is 8, then this function will return 6561,

If base is 3 and exp is 9, then this function will return 19683.

Code of powerRecursive()

unsigned long powerRecursive( int base , int exp )

{

      if ( exp == 0 )

            return 1;

      else

            return base * powerRecursive( base , exp - 1 );

}

Summary of powerRecursive()

powerRecursive() is a recursive function with 2 parts;

first part is the base case – if the exponent is equal to 0, then this function will return 1.

powerRecursive ( 0 ) = 1

Second part consists of recursive calls as mentioned below:

base * powerRecursive ( base , exp - 1 )

Example (C++)

#include "stdafx.h"

#include "iostream"

#include "conio.h"

using namespace std;

unsigned long powerRecursive( int base , int exp )

{

      if ( exp == 0 )

            return 1;

      else

            return base * powerRecursive( base , exp - 1 );

}

int main()

{

      for( int i = 0; i < 10; i++  )

            cout << 3 << "^" << i << ":" << powerRecursive( 3 , i ) << endl;

      cout << endl;

      _getche();

      return 0;

}

Output

3^0:1

3^1:3

3^2:9

3^3:27

3^4:81

3^5:243

3^6:729

3^7:2187

3^8:6561

3^9:19683