一定得注意取值，当指数小于0，指数大于0，指数等于0时
如果指数和底数都是0时怎么办，还有浮点数的比较
#include <stdio.h> #define ESP 0.0000001 typedef enum bool{ false = 0, true = 1 }bool; bool value_num = false; //定义一个全局变量用来区分正确时返回的0和错误时返回的0 double PowWithunsignedexp(double Base, unsigned int exp); bool equal(double One, double Two); double MyPow (double Base, int exp) { bool value_num = true; double result; unsigned int unsignedexp; if ( equal(Base,0.0) && exp == 0) { value_num = false; return 0.0; //指数和底数都是0时返回0，value_num为false说明传值错误 } if (exp == 0) return 1.0; else if (exp < 0) unsignedexp = (unsigned int)(-exp); //指数为负数时取绝对值 else unsignedexp = (unsigned int)(exp); result = PowWithunsignedexp (Base,unsignedexp); if(exp < 0) return (1/result); else return result; } double PowWithunsignedexp(double Base, unsigned int exp) //用递归求幂，因为指数为大于0的指数，有奇数和偶数两种情况 { if (exp == 1) return Base; else if (exp%2 == 0) return PowWithunsignedexp(Base,exp/2)*PowWithunsignedexp(Base,exp/2); else return PowWithunsignedexp(Base,exp/2)*PowWithunsignedexp(Base,(exp/2+1)); } bool equal(double One, double Two) //比较浮点数的大小 { if ((One - Two) <= ESP && (Two - One) <= ESP) return true; return false; }