问一下这个程序为什么会错呢

Question

 #include<stdio.h>
#include<ctype.h>
/*获取小数*/
/*
double getfloat(double *pn)
{
    char c;int sign;
    while (isspace(c = getchar()))
        ;
    if (isdigit(c) || c == '.' || c == '-')
    {
        if (c == '-')
        {
            sign = -1;
        }
        else if (c == '.')
        {
            int power=1;
            while ((c = getchar()) != EOF&&isdigit(c))
            {
                *pn = *pn * 10 + (c - '0');
                power *= 10;
             }
            printf("++%lf", *pn);
            *pn = (*pn / power);    printf("%lf", *pn);
            return *pn;
        }
        else
        {
            double temp=0.0;
            for(;isdigit(c);c=getchar())
            {
                *pn = *pn * 10 + (c - '0');
            }
            double power = 0.0;
            if (c == '.')
            {
                c = getchar();
                for (;isdigit(c);c = getchar())
                {
                    temp = 10 * temp + (c - '0');
                    power *= 10;
                }
            }
            *pn = (*pn + temp / power); 
            return *pn;
        }
    }
    else
    {
        return -1;
    }
}
int main(void)
{
    double p = 0.0;
    double *pn = &p;
    double c=getfloat(pn);
    printf("%lf",c);
}

Answer 1

出错会有调试信息的，学着去根据提示信息定位错误。