Need Dev C++ Help

[Doj23TCk]

How would you write this code using a recursive function?

#include <stdio.h>
double power(double a, int b);
int main()
{
double x, powr;
int n;
printf("Enter a number and the integer base and then the power\n");
while (scanf("%lf%d", &x, &n) == 2)
{
powr = power(x,n);
printf("%.3g to the power %d is %.5g\n", x, n, powr);
printf("Enter the next pair of numbers\n");

}
return 0;
}
double power(double a, int b)
{
double powr = 1;
int i;

if (b == 0)
{
if (a == 0)
printf("0 to the 0 undefined; using 1 as the value\n");
powr = 1.0;
}
else if (a == 0)
powr = 0.0;
else if (b > 0)
for(i = 1; i <= b; i++)
powr *= a;
else
powr = 1.0 / power(a, - b);
return powr;
}

[JLBorges]

double power( double a, unsigned int b ) // logarithmic complexity
{
    if( b == 0 )
    {
        // https://en.wikipedia.org/wiki/NaN
        if( a == 0 ) return 0 / 0.0  ; // NaN (not a number)
        else return 1 ;
    }

    else if( b == 1 ) return a ;

    else return power( a, b/2 ) * power( a, (b+1)/2 ) ; // O(log N)
}

double power_bf( double a, unsigned int b ) // linear complexity
{
    if( b == 0 )
    {
        if( a == 0 ) return 0 / 0.0  ; // NaN (not a number)
        else return 1 ;
    }

    else return a * power_bf( a, b-1 ) ; // O(N)
}

[Doj23TCk]

I tired it out but I kept on getting some errors. So I played around with it and still didn't get anything.

[JLBorges]

You may want to post your code, accompanied by the text of the error messages that you received.

[Doj23TCk]

wait so the recursive thing that you showed is that something you would replace with the original code so maybe look something like...
#include <stdio.h>
double power(double a, int b);
int main()
{
double x, powr;
int n;
printf("Enter a number and the integer base and then the power\n");
while (scanf("%lf%d", &x, &n) == 2)
{
powr = power(x,n);
printf("%.3g to the power %d is %.5g\n", x, n, powr);
printf("Enter the next pair of numbers\n");

}
return 0;
}
double power( double a, unsigned int b )
{
if( b == 0 )
{

if( a == 0 ) return 0 / 0.0 ;
else return 1 ;
}

else if( b == 1 ) return a ;

else return power( a, b/2 ) * power( a, (b+1)/2 );
}

double power_bf( double a, unsigned int b )
{
if( b == 0 )
{
if( a == 0 ) return 0 / 0.0 ;
else return 1 ;
}

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

[JLBorges]

#include <stdio.h>

double power(double a, unsigned int b); // *** unsigned int

int main()
{
    double x ; // , powr;
    unsigned int n; // *** unsigned int

    puts( "Enter a number (base) and the non-negative integer exponent");
    while( scanf("%lf%u", &x, &n) == 2 ) // %u for unsigned int
    {
        const double powr = power(x,n);
        printf("%.3g to the power %u is %.5g\n", x, n, powr); // %u
        printf("Enter the next pair of numbers\n");
    }
    return 0;
}

double power( double a, unsigned int b )
{
    if( b == 0 )
    {
        if( a == 0 ) return 0 / 0.0 ;
        else return 1 ;
    }

    else if( b == 1 ) return a ;

    else return power( a, b/2 ) * power( a, (b+1)/2 );
}

/*
double power_bf( double a, unsigned int b )
{
    if( b == 0 )
    {
        if( a == 0 ) return 0 / 0.0 ;
        else return 1 ;
    }

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