Recursion: Power Function

/* POWER.C */

# include

double power_f(double, float );

/* Definition of the function power_f() */

double power_f(double a, float b)
{
 if( b == 0)
 {
  return 1;
 }
 else if ( b< 0)
 {
  return( (a * power_f(a,b+1)));
 }

 else
  return( a* power_f(a,b-1));
}

/* Function main */

void main()
{
 double mantissa;
 float exponent;

 printf("\n Input the Mantissa: ");
 scanf("%lf", &mantissa);
 printf("\n Input the exponent: ");
 scanf("%f", &exponent);
 if( exponent < 0)
  printf("\n maintissa ^ exponent: %lf", 1/ power_f(mantissa, exponent));
 else printf("\n maintissa ^ exponent: %lf", power_f(mantissa, exponent));
}

An Alternative

/* POWER1.C */

# include
# include

double power_fract(double, float, float );
void expo();

/* The definition of the power_fract() function */

double power_fract(double a, float b, float i)
{
 if( b == 0)
 {
  return 1;
 }
 else if ( b< 0)
 {
  return( (a * power_fract(a,b + i,i)));
 }

 else
  return( a* power_fract(a,b - i,i));
}

/* The definition of the expo() function */

void expo()
{
 char str[50];
 char *pstr;
 char temp;
 int count = 0;
 char ch;
 int i = 0;
 float counter;
 float exponent;
 float mantissa;
 printf("\n Input the Mantissa: ");
 scanf("%f", &mantissa);
 printf(" Input the Exponent: ");
 fflush(stdin);

 ch = getchar();

 while( ch != '\n')
 {
  if((ch == '-') || (ch == '+'))
   count--;
  if( ch == '.')
   temp = ch;
  str[i] = ch;
  ch = getchar();
  i ++;
  count ++;
 }
 str[i]='\0';
 printf("\n\n Number of digits including '.' = %d", count);
 count = i;
 if (temp == '.')
 {
  i = 1;
  pstr = &str[0];
  while(*pstr != '.')
  {
   pstr++;
   i ++;
  }
 }
 printf("\n Number of digits including sign & period(.) character = %d",i);
 count = count - i;
 printf("\n Number of digits after decimal point = %d", count);
 exponent = atof(str);
 counter = 1/power_fract(10, -count,1);
 printf("\n Increment/Decrement counter = %f", counter);
 printf("\n\n Mantissa = %f", mantissa);
 printf("\n Exponent = %f", exponent);

 if(exponent < 0)
  printf("\n\n mantissa ^ exponent = %lf", 1/power_fract(mantissa,exponent,counter));
 else
  printf("\n\n mantissa ^ exponent = %lf", power_fract(mantissa,exponent,counter));
}

// Function main

void main()
{
 expo();
}