Create a recursive power function. - C Function

C examples for Function:Utility Function

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Description

Create a recursive power function.

Demo Code

#include <stdio.h>
#include <stdlib.h> // prototype for abs() 

double power(double base, int exponent);

int main(void)
{
  double base, output;
  int exponent;//from  ww  w. ja  v  a  2s .  c o m

  printf("Enter a :double: base and :int: exponent: ");

  while (scanf("%lf %d", &base, &exponent) == 2){
    output = power(base, exponent);

    printf("%f ^ %d = %f \n", base, exponent, output);

    printf("Enter a :double: base and :int: exponent: ");
  }

  return 0;
}

double power(double base, int exponent){
  double dbl_power;

  // handle powers of zero
  if (base == 0){
    if (exponent == 0){
      printf("Warning: 0 ^ 0 is undefined. Using 1.\n");
      return 1.0;
    }
    else
      return 0;
  }

  if (exponent == 0) 
     return 1; // stop recursion

  dbl_power = base * power(base, abs(exponent) - 1); // recursion step

  // if exponent is negative, take reciprocal
  if (exponent < 0) 
     dbl_power = 1 / dbl_power;

  return dbl_power;
}

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