//实现函数，求base的exponent次方.
double Power(double base, int exponent)
{
if(equal(base, 0.0))
{
if(exponent < 0)
{
throw std::exception("invalid exponent.\n");
}
else if(exponent >= 0)
{
return 0.0;
}
}
unsigned int absExponent = (unsigned int) exponent;
if(exponent < 0)
{
absExponent = (unsigned int)(- exponent);
}
double result = PowerWithUnsignedExponent(base, absExponent);
if(exponent < 0)
{
result = 1.0 / result;
}
return result;
}
double Power(double base, int exponent)
{
if (equal(base, 0) && exponent < 0)
{
g_InvalidInput = 1;
return 0.0;
}
unsigned unsigned_exponent = exponent < 0 ? (unsigned int)-exponent : (unsigned int)exponent;
double result = PowerWithUnsignedExponent(base, unsigned_exponent);
if (exponent<0)
{
result = 1.0 / result;
}
return result;
}
double Power(double base, int exponent)
{
if(equal(base, 0.0) && exponent < 0)
{
return std::numeric_limits<double>::quiet_NaN();
}
unsigned int absExponent = (unsigned int)(exponent);
if(exponent < 0)
absExponent = (unsigned int)(-exponent);
double result = PowerWithUnsignedExponent(base, absExponent);
if(exponent < 0)
result = 1.0/result;
return result;
}
double pow(double x, int n) {
bool g_InvalidInput = false;
if(equal(n,0.0) && n < 0){
g_InvalidInput = true;
return 0.0;
}
unsigned int absExponent = (unsigned int) (n);
if(n < 0)
absExponent =(unsigned int)(-n);
double ret = PowerWithUnsignedExponent(x,absExponent);
if(n < 0)
ret = 1.0/ret;
return ret;
}
