大数模板 大数加法，大数减法，大数乘法，大数除法，大数比较等操作

实现了一个大数模板类，包括加减乘除，求余，比较大小等等操作。

#include<iostream> #include<string> #include<iomanip> #include<algorithm> using namespace std; #define MAXN 9999#define MAXSIZE 10#define DLEN 4class CalBigNum{ private: int a[500];    //可以控制大数的位数 int len;       //大数长度public: CalBigNum(){ len = 1;memset(a,0,sizeof(a)); }   //构造函数CalBigNum(const int);       //将一个int类型的变量转化为大数CalBigNum(const char*);     //将一个字符串类型的变量转化为大数CalBigNum(const CalBigNum &);  //拷贝构造函数CalBigNum &operator=(const CalBigNum &);   //重载赋值运算符，大数之间进行赋值运算friend istream& operator>>(istream&,  CalBigNum&);   //重载输入运算符friend ostream& operator<<(ostream&,  CalBigNum&);   //重载输出运算符CalBigNum operator+(const CalBigNum &) const;   //重载加法运算符，两个大数之间的相加运算 CalBigNum operator-(const CalBigNum &) const;   //重载减法运算符，两个大数之间的相减运算 CalBigNum operator*(const CalBigNum &) const;   //重载乘法运算符，两个大数之间的相乘运算 CalBigNum operator/(const int   &) const;    //重载除法运算符，大数对一个整数进行相除运算CalBigNum operator^(const int  &) const;    //大数的n次方运算int    operator%(const int  &) const;    //大数对一个int类型的变量进行取模运算    bool   operator>(const CalBigNum & T)const;   //大数和另一个大数的大小比较bool   operator>(const int & t)const;      //大数和一个int类型的变量的大小比较void print();       //输出大数}; CalBigNum::CalBigNum(const int b)     //将一个int类型的变量转化为大数{ int c,d = b;len = 0;memset(a,0,sizeof(a));while(d > MAXN){c = d - (d / (MAXN + 1)) * (MAXN + 1); d = d / (MAXN + 1);a[len++] = c;}a[len++] = d;}CalBigNum::CalBigNum(const char*s)     //将一个字符串类型的变量转化为大数{int t,k,index,l,i;memset(a,0,sizeof(a));l=strlen(s);   len=l/DLEN;if(l%DLEN)len++;index=0;for(i=l-1;i>=0;i-=DLEN){t=0;k=i-DLEN+1;if(k<0)k=0;for(int j=k;j<=i;j++)t=t*10+s[j]-'0';a[index++]=t;}}CalBigNum::CalBigNum(const CalBigNum & T) : len(T.len)  //拷贝构造函数{ int i; memset(a,0,sizeof(a)); for(i = 0 ; i < len ; i++)a[i] = T.a[i]; } CalBigNum & CalBigNum::operator=(const CalBigNum & n)   //重载赋值运算符，大数之间进行赋值运算{int i;len = n.len;memset(a,0,sizeof(a)); for(i = 0 ; i < len ; i++) a[i] = n.a[i]; return *this; }istream& operator>>(istream & in,  CalBigNum & b)   //重载输入运算符{char ch[MAXSIZE*4];int i = -1;in>>ch;int l=strlen(ch);int count=0,sum=0;for(i=l-1;i>=0;){sum = 0;int t=1;for(int j=0;j<4&&i>=0;j++,i--,t*=10){sum+=(ch[i]-'0')*t;}b.a[count]=sum;count++;}b.len =count++;return in;}ostream& operator<<(ostream& out,  CalBigNum& b)   //重载输出运算符{int i;  cout << b.a[b.len - 1]; for(i = b.len - 2 ; i >= 0 ; i--){ cout.width(DLEN); cout.fill('0'); cout << b.a[i]; } return out;}CalBigNum CalBigNum::operator+(const CalBigNum & T) const   //两个大数之间的相加运算{CalBigNum t(*this);int i,big;      //位数   big = T.len > len ? T.len : len; for(i = 0 ; i < big ; i++) { t.a[i] +=T.a[i]; if(t.a[i] > MAXN) { t.a[i + 1]++; t.a[i] -=MAXN+1; } } if(t.a[big] != 0)t.len = big + 1; elset.len = big;   return t;}CalBigNum CalBigNum::operator-(const CalBigNum & T) const   //两个大数之间的相减运算 {  int i,j,big;bool flag;CalBigNum t1,t2;if(*this>T){t1=*this;t2=T;flag=0;}else{t1=T;t2=*this;flag=1;}big=t1.len;for(i = 0 ; i < big ; i++){if(t1.a[i] < t2.a[i]){ j = i + 1; while(t1.a[j] == 0)j++; t1.a[j--]--; while(j > i)t1.a[j--] += MAXN;t1.a[i] += MAXN + 1 - t2.a[i]; } elset1.a[i] -= t2.a[i];}t1.len = big;while(t1.a[t1.len - 1] == 0 && t1.len > 1){t1.len--; big--;}if(flag)t1.a[big-1]=0-t1.a[big-1];return t1; } CalBigNum CalBigNum::operator*(const CalBigNum & T) const   //两个大数之间的相乘运算 { CalBigNum ret; int i,j,up; int temp,temp1;   for(i = 0 ; i < len ; i++){ up = 0; for(j = 0 ; j < T.len ; j++){ temp = a[i] * T.a[j] + ret.a[i + j] + up; if(temp > MAXN){ temp1 = temp - temp / (MAXN + 1) * (MAXN + 1); up = temp / (MAXN + 1); ret.a[i + j] = temp1; } else{ up = 0; ret.a[i + j] = temp; } } if(up != 0) ret.a[i + j] = up; } ret.len = i + j; while(ret.a[ret.len - 1] == 0 && ret.len > 1)ret.len--; return ret; } CalBigNum CalBigNum::operator/(const int & b) const   //大数对一个整数进行相除运算{ CalBigNum ret; int i,down = 0;   for(i = len - 1 ; i >= 0 ; i--){ ret.a[i] = (a[i] + down * (MAXN + 1)) / b; down = a[i] + down * (MAXN + 1) - ret.a[i] * b; } ret.len = len; while(ret.a[ret.len - 1] == 0 && ret.len > 1)ret.len--; return ret; }int CalBigNum::operator %(const int & b) const    //大数对一个int类型的变量进行取模运算    {int i,d=0;for (i = len-1; i>=0; i--){d = ((d * (MAXN+1))% b + a[i])% b;  }return d;}CalBigNum CalBigNum::operator^(const int & n) const    //大数的n次方运算{CalBigNum t,ret(1);int i;if(n<0)exit(-1);if(n==0)return 1;if(n==1)return *this;int m=n;while(m>1){t=*this;for( i=1;i<<1<=m;i<<=1){t=t*t;}m-=i;ret=ret*t;if(m==1)ret=ret*(*this);}return ret;}bool CalBigNum::operator>(const CalBigNum & T) const   //大数和另一个大数的大小比较{ int ln; if(len > T.len)return true; else if(len == T.len){ ln = len - 1; while(a[ln] == T.a[ln] && ln >= 0)ln--; if(ln >= 0 && a[ln] > T.a[ln])return true; elsereturn false; } elsereturn false; }bool CalBigNum::operator >(const int & t) const    //大数和一个int类型的变量的大小比较{CalBigNum b(t);return *this>b;}void CalBigNum::print()    //输出大数{ int i;   cout << a[len - 1]; for(i = len - 2 ; i >= 0 ; i--){ cout.width(DLEN); cout.fill('0'); cout << a[i]; } cout << endl;}int main(void){int i,n;        CalBigNum x,y,sum,dif,mul,div;<span style="white-space:pre"></span>cin>>x;<span style="white-space:pre"></span>cin>>y;<span style="white-space:pre"></span>sum = x+y;<span style="white-space:pre"></span>dif = x-y;<span style="white-space:pre"></span>mul=x*y;<span style="white-space:pre"></span>div=x/y;<span style="white-space:pre"></span>cout<<”sum=”<<sum<<” dif=”<<dif<<” mul=”<<mul<<” div=”<<div<<endl;CalBigNum x[101];      //定义大数的对象数组x[0]=1;for(i=1;i<101;i++)x[i]=x[i-1]*(4*i-2)/(i+1);while(scanf("%d",&n)==1 && n!=-1){x[n].print();}}