// 面试题16：数值的整数次方

 // 题目：实现函数double Power(double base, int exponent)，求base的exponent

 // 次方。不得使用库函数，同时不需要考虑大数问题。

 #include <iostream>

 #include <cmath>

 bool g_InvalidInput = false;

 bool equal(double num1, double num2);

 double PowerWithUnsignedExponent(double base, unsigned int exponent);

 double Power(double base, int exponent)

 {

     g_InvalidInput = false;

     if (equal(base, 0.0) && exponent < )

     {

         g_InvalidInput = true;

         return 0.0;

     }

     unsigned int absExponent = (unsigned int) (exponent);

     if (exponent < )

         absExponent = (unsigned int) (-exponent);

     double result = PowerWithUnsignedExponent(base, absExponent);

     if (exponent < )

         result = 1.0 / result;

     return result;

 }

 /*

 double PowerWithUnsignedExponent(double base, unsigned int exponent)

 {

     double result = 1.0;

     for (int i = 1; i <= exponent; ++i)

         result *= base;

     return result;

 }

 */

 double PowerWithUnsignedExponent(double base, unsigned int exponent)

 {

     if (exponent == )

         return ;

     if (exponent == )

         return base;

     double result = PowerWithUnsignedExponent(base, exponent >> );

     result *= result;

     if ((exponent & 0x1) == )

         result *= base;

     return result;

 }

 bool equal(double num1, double num2)

 {

     if ((num1 - num2 > -0.0000001) && (num1 - num2 < 0.0000001))

         return true;

     else

         return false;

 }

 // ====================测试代码====================

 void Test(const char* testName, double base, int exponent, double expectedResult, bool expectedFlag)

 {

     double result = Power(base, exponent);

     if (equal(result, expectedResult) && g_InvalidInput == expectedFlag)

         std::cout << testName << " passed" << std::endl;

     else

         std::cout << testName << " FAILED" << std::endl;

 }

 int main(int argc, char* argv[])

 {

     // 底数、指数都为正数

     Test("Test1", , , , false);

     // 底数为负数、指数为正数

     Test("Test2", -, , -, false);

     // 指数为负数

     Test("Test3", , -, 0.125, false);

     // 指数为0

     Test("Test4", , , , false);

     // 底数、指数都为0

     Test("Test5", , , , false);

     // 底数为0、指数为正数

     Test("Test6", , , , false);

     // 底数为0、指数为负数

     Test("Test7", , -, , true);

     return ;

 }

 #include"iostream"

 #include"stdio.h"

 #include"stdexcept"

 using namespace std;

 bool errorFlag=false;

 double GetPower(double base,int exponent)

 {

     if(exponent==)

         return 1.0;

     if(exponent==)

         return base;

     double result=GetPower(base,exponent>>);

     result*=result;

     if(exponent&)

         result*=base;

     return result;

 }

 bool Equal(double num1,double num2)

 {

     if((num1-num2)>-0.000001&&(num1-num2)<0.000001)

         return true;

     return false;

 }

 double Power(double base,int exponent)

 {

     errorFlag=false;

     double result=;

   //  cout<<exponent<<endl;

     if(Equal(base,)&&exponent<)

     {

         errorFlag=true;

         return ;

     }

     if(exponent<)

     {

         result=1.0/GetPower(base,-exponent);

     }

     else

     {

         result=GetPower(base,exponent);

     }

     return result;

 }

 void Test(char *testName,double base,int exponent,double expectResult,bool expectFlag)

 {

     //注意这里需要后判断flag，不然前面函数没执行，errorFlag值不会得到更新

     if(Equal(Power(base,exponent),expectResult)&&errorFlag==expectFlag)

     {

         cout<<testName<<":passed."<<endl;

     }

     else

     {

         cout<<testName<<":failed."<<endl;

     }

 }

 int main()

 {

     Test("Test1",-,-,0.25,false);

     Test("Test2",-,,-,false);

     Test("Test3",-,,,false);

     Test("Test4",,-,,true);

     Test("Test5",,,,false);

     Test("Test6",,,,false);

     Test("Test7",,,,false);

     Test("Test8",,-,0.5,false);

     Test("Test9",,,,false);

     return ;

 }