#include <iostream>  #include <cstdlib>  #include <ctime>  using namespace std;     /*  This is a free Program, You can modify or redistribute it under the terms of GNU  *Description:一种改进的求整数x的y次幂  *Language: C++  *Development Environment: VC6.0  *Author: Wangzhicheng  *E-mail: 2363702560@qq.com  *Date: 2012/10/14  */     /*  核心方法是利用乘方的性质  当x求出,x^2=x*x,当x^2求出,x^4=(x^2)*(x^2) ,依次类推  */     const int max=100000000;  //底数最大的数     class Power {  private:      int base;       //底数      int exponent;    //指数      long result;    //存放结果  public:      Power(int b,int e) {          if(b<0 || b>=max) {              cerr<<"底数应该大于等于0且小于"<<max<<endl;              exit(1);          }          if(e<0 || e>max/10000) {              cerr<<"指数应该大于等于0且小于"<<(max/10000)<<endl;              exit(1);          }          base=b;          exponent=e;      }      void power() {          int result=1;          power(exponent,result);          setResult(result);          show();      }      void power_common() {          int i;          int result=1;          for(i=0;i<exponent;i++) {              result=result*base;          }          setResult(result);          show();      }      void show() {          if(result<0) {              cerr<<"结果溢出!"<<endl;              result=0;              return;          }          cout<<"power("<<base<<","<<exponent<<")="<<result<<endl;      }  private:      void setResult(int r) {          result=r;      }      void power(int exponent,int &result) {          int pre=1;     //前面值          int temp=base;    //每一位对应的权值          while(exponent) {              if(exponent%2) {                  result=pre*temp;                  pre=result;              }              temp=temp*temp;              exponent/=2;          }      }  };     void main() {      srand(unsigned(time(0)));      int i;      int x,y;      const int N=10;      for(i=0;i<N;i++) {          x=rand()%(N*N);          y=rand()%N;          Power power(x,y);          power.power();          power.power_common();      }  }