C primer plus(第六版） 编程练习 第九章 第八题

/*    6.20    */
#include<stdio.h>
double power(double n,int p);
int main(void)
{
	double x, xpow;
	int exp;

	printf("Enter a number and the positive integer power");
	printf(" to which\nthe number will be raised. Enter q");
	printf(" to quit.\n");
	while (scanf("%lf %d",&x, &exp) == 2)
	{
		xpow = power(x, exp);
		printf("%.3g to the power %d is %.5g\n",x, exp, xpow);
		printf("Enter next pair of numbers or q to quit.\n");
	}
	printf("Hope you enjoyed this power trip -- bye!\n");

	return 0;
}
double power(double n,int p)
{
	double pow ;double sum;
if(p>0){

		pow = n* power(n,p-1);
}
else if(p==0)pow=1;
else if(p<0){

    pow=1/n* power(n,p+1);
}
	return pow;
}