BigInteger从Java移植到cpp，自己写了两天，写崩了。。。

自己的：

const int LEN=100;
typedef struct HighPrecision
{
	short data[LEN],h;
	HighPrecision()
	{
		CLEAR(data);
		h=0;
	}
	HighPrecision(int n)
	{
		CLEAR(data);
		h=0;
		while(n>0) data[h++]=n%10,n/=10;
		if(!data[h]) h--;
	}
	/*HighPrecision(const HighPrecision &a)
	{
		memcpy(data,a.data,sizeof(data));
		h=a.h;
	}*/
	const HighPrecision &operator= (int n)
	{
		CLEAR(data);
		h=0;
		while(n>0) data[h++]=n%10,n/=10;
		if(!data[h]) h--;
		return *this;
	}
	const HighPrecision &operator= (const HighPrecision &a)
	{
		memcpy(data,a.data,sizeof(data));
		h=a.h;
		return *this;
	}
	bool odd()
	{
		return data[0]&1;
	}
	void output()
	{
		for(int i=h;i>=0;i--) printf("%d",data[i]);
	}
} BigInteger;

bool operator< (const BigInteger &a,const BigInteger &b)
{
	if (a.h<b.h) return 1;
	else if (a.h>b.h) return 0;
	else
	{
		int h=b.h,k=0;
		for(int i=h;i>=0;i--)
			if (a.data[i]!=b.data[i]) {k=i;break;}
		return a.data[k]<b.data[k];
	}
}

bool operator< (const BigInteger &a,int n)
{
	return a<BigInteger(n);
}

bool operator> (const BigInteger &a,const BigInteger &b)
{
	if (a.h<b.h) return 0;
	else if (a.h>b.h) return 1;
	else
	{
		int h=b.h,k=0;
		for(int i=h;i>=0;i--)
			if (a.data[i]!=b.data[i]) {k=i;break;}
		return a.data[k]>b.data[k];
	}
}

bool operator> (const BigInteger &a,int n)
{
	return a>BigInteger(n);
}

bool operator== (const BigInteger &a,const BigInteger &b)
{
	if (a.h!=b.h) return 0;
	else
	{
		int h=b.h,k=0;
		for(int i=h;i>=0;i--)
			if (a.data[i]!=b.data[i]) {k=i;break;}
		return a.data[k]==b.data[k];
	}
}

bool operator== (const BigInteger &a,int n)
{
	return a==BigInteger(n);
}

bool operator>= (const BigInteger &a,const BigInteger &b)
{
	return (a>b)||(a==b);
}

BigInteger operator+(const BigInteger &a,const BigInteger &b)
{
	BigInteger c;
	int h=max(a.h,b.h);
	for(int i=0;i<=h;i++)
	{
		c.data[i]+=a.data[i]+b.data[i];
		c.data[i+1]=c.data[i]/10;
		c.data[i]%=10;
	}
	while(c.data[c.h+1]>0) c.h++;
	return c;
}

BigInteger operator+(const BigInteger &a,int n)
{
	return a+BigInteger(n);
}

BigInteger operator+= (const BigInteger &a,const BigInteger &b)
{
	return a+b;
}

BigInteger operator-(const BigInteger &a,const BigInteger &b)
{
	BigInteger c(a);
	int h=c.h;
	for(int i=0;i<=c.h;i++)
	{
		c.data[i]-=b.data[i];
		if (c.data[i]<0)
		{
			c.data[i]+=10;
			c.data[i+1]--;
		}
	}
	while(c.data[c.h]<1) c.h--;
	return c;
}

BigInteger operator-(const BigInteger &a,int n)
{
	return a-BigInteger(n);
}

BigInteger operator-= (const BigInteger &a,const BigInteger &b)
{
	return a-b;
}

BigInteger operator* (const BigInteger &a,const BigInteger &b)
{
	BigInteger c;
	for(int i=0;i<=a.h;i++)
		for(int j=0;j<=b.h;j++)
			c.data[i+j-1]+=a.data[i]*b.data[j];
	int k=0;
	while(c.data[k++]>0)
	{
		c.data[k+1]+=c.data[k]/10;
		c.data[k]%=10;
	}
	c.h=(k-1>=0)?k-1:0;
	return c;
}

BigInteger operator*= (const BigInteger &a,const BigInteger &b)
{
	return a*b;
}

BigInteger operator/ (const BigInteger &a,const BigInteger &b)
{
	BigInteger c,tmp;
	int h=max(a.h,b.h);
	for( int i = h; i >= 0; i-- ){
		tmp*= 10;
		tmp+= a.data[i];
		while( tmp >= b ) { tmp -= b; c.data[i]++; }
	}
	c.h=a.h;
	while(c.data[c.h]<1) c.h--;
	return c;
}

BigInteger operator/ (const BigInteger &a,int n)
{
	return a/BigInteger(n);
}

BigInteger operator/= (const BigInteger &a,const BigInteger &b)
{
	return a/b;
}

BigInteger operator% (const BigInteger &a,const BigInteger &b)
{
	BigInteger c,tmp;
	int h=max(a.h,b.h);
	for( int i = h; i >= 0; i-- ){
		tmp*= 10;
		tmp+= a.data[i];
		while( tmp >= b ) { tmp -= b; c.data[i]++; }
	}
	tmp.h=a.h;
	while(tmp.data[tmp.h]<1) tmp.h--;
	return tmp;
}

BigInteger operator>>(const BigInteger &a,int n)
{
	BigInteger c(a);
	for (int i=1;i<=n;i++) c=c/2;
	return c;
}

别人的：

http://blog.csdn.net/wall_f/article/details/8373395

const int MAXN = 410;

struct bign
{
	int len, s[MAXN];
	bign ()
	{
		memset(s, 0, sizeof(s));
		len = 1;
	}
	bign (int num) { *this = num; }
	bign (const char *num) { *this = num; }
	bign operator = (const int num)
	{
		char s[MAXN];
		sprintf(s, "%d", num);
		*this = s;
		return *this;
	}
	bign operator = (const char *num)
	{
		for(int i = 0; num[i] == '0'; num++) ;  //去前导0
		len = strlen(num);
		for(int i = 0; i < len; i++) s[i] = num[len-i-1] - '0';
		return *this;
	}
	bign operator + (const bign &b) const //+
	{
		bign c;
		c.len = 0;
		for(int i = 0, g = 0; g || i < max(len, b.len); i++)
		{
			int x = g;
			if(i < len) x += s[i];
			if(i < b.len) x += b.s[i];
			c.s[c.len++] = x % 10;
			g = x / 10;
		}
		return c;
	}
	bign operator += (const bign &b)
	{
		*this = *this + b;
		return *this;
	}
	void clean()
	{
		while(len > 1 && !s[len-1]) len--;
	}
	bign operator * (const bign &b) //*
	{
		bign c;
		c.len = len + b.len;
		for(int i = 0; i < len; i++)
		{
			for(int j = 0; j < b.len; j++)
			{
				c.s[i+j] += s[i] * b.s[j];
			}
		}
		for(int i = 0; i < c.len; i++)
		{
			c.s[i+1] += c.s[i]/10;
			c.s[i] %= 10;
		}
		c.clean();
		return c;
	}
	bign operator *= (const bign &b)
	{
		*this = *this * b;
		return *this;
	}
	bign operator - (const bign &b)
	{
		bign c;
		c.len = 0;
		for(int i = 0, g = 0; i < len; i++)
		{
			int x = s[i] - g;
			if(i < b.len) x -= b.s[i];
			if(x >= 0) g = 0;
			else
			{
				g = 1;
				x += 10;
			}
			c.s[c.len++] = x;
		}
		c.clean();
		return c;
	}
	bign operator -= (const bign &b)
	{
		*this = *this - b;
		return *this;
	}
	bign operator / (const bign &b)
	{
		bign c, f = 0;
		for(int i = len-1; i >= 0; i--)
		{
			f = f*10;
			f.s[0] = s[i];
			while(f >= b)
			{
				f -= b;
				c.s[i]++;
			}
		}
		c.len = len;
		c.clean();
		return c;
	}
	bign operator /= (const bign &b)
	{
		*this  = *this / b;
		return *this;
	}
	bign operator % (const bign &b)
	{
		bign r = *this / b;
		r = *this - r*b;
		return r;
	}
	bign operator %= (const bign &b)
	{
		*this = *this % b;
		return *this;
	}
	bool operator < (const bign &b)
	{
		if(len != b.len) return len < b.len;
		for(int i = len-1; i >= 0; i--)
		{
			if(s[i] != b.s[i]) return s[i] < b.s[i];
		}
		return false;
	}
	bool operator > (const bign &b)
	{
		if(len != b.len) return len > b.len;
		for(int i = len-1; i >= 0; i--)
		{
			if(s[i] != b.s[i]) return s[i] > b.s[i];
		}
		return false;
	}
	bool operator == (const bign &b)
	{
		return !(*this > b) && !(*this < b);
	}
	bool operator != (const bign &b)
	{
		return !(*this == b);
	}
	bool operator <= (const bign &b)
	{
		return *this < b || *this == b;
	}
	bool operator >= (const bign &b)
	{
		return *this > b || *this == b;
	}
	string str() const
	{
		string res = "";
		for(int i = 0; i < len; i++) res = char(s[i]+'0') + res;
		return res;
	}
};

istream& operator >> (istream &in, bign &x)
{
	string s;
	in >> s;
	x = s.c_str();
	return in;
}

ostream& operator << (ostream &out, const bign &x)
{
	out << x.str();
	return out;
}

int main()
{
	bign a, b, c, d, e, f, g;
	while(cin>>a>>b)
	{
		a.clean(), b.clean();
		c = a+b;
		d = a-b;
		e = a*b;
		f = a/b;
		g = a%b;
		cout<<"a+b"<<"="<<c<<endl; // a += b
		cout<<"a-b"<<"="<<d<<endl; // a -= b;
		cout<<"a*b"<<"="<<e<<endl; // a *= b;
		cout<<"a/b"<<"="<<f<<endl; // a /= b;
		cout<<"a%b"<<"="<<g<<endl; // a %= b;
		if(a != b) printf("YES\n");
		else printf("NO\n");
	}
	return 0;
}