2^n的一个生成器

 2009-03-24 16:25

#include<iostream>
#include<fstream>
using namespace std;

struct BigNum{
       int len,num[600];
       BigNum(){
             len = 1;
             memset(num,0,sizeof(num) );
       }
};

const int SIZE = 1000;

ostream& operator<<(ostream& out,const BigNum& n);
void operator*=(BigNum& n,int t);

int main(void){
    BigNum N;
    ofstream out("2^n.out");
   
    N.num[0] = 1;
    for(int i=0;i<SIZE;i++){
        out<<N<<endl<<endl;
        N *= 2;
    }
    out<<N;
   
    return 0;
}

void operator*=(BigNum& n,int t){
     int i,j;
    
     for(i=0;i<n.len;i++)
         n.num[i]*=t;
        
     for(i=0;i<n.len;i++){
         n.num[i+1] += n.num[i]/10;
         n.num[i] %= 10;
     }
    
     if(n.num[n.len]>0) n.len++;
}

ostream& operator<<(ostream& out,const BigNum& n){
         for(int i=n.len-1;i>=0;i--)
             out<<n.num[i];
            
         return out;
}