基于C++的大整数运算操作

主要思想是模拟手算，不知道还有没有未发现的bug，发现了也不要用告诉我了，就是这么任性。

#include <iostream>#include <cstring>using namespace std;#define maxn 5005class BigInteger{private: int len; //记录数据实际长度 int data[maxn]; //记录数据，低位在前，高位在后 bool positive; //标记正或负private: void toInt(char *); void toStr(char *); BigInteger plus(BigInteger a); BigInteger minus(BigInteger a);public: BigInteger(); BigInteger(char *s); BigInteger(int a); friend istream& operator >> (istream &in, BigInteger &a); friend ostream& operator << (ostream &out, BigInteger &a); BigInteger operator + (BigInteger a); BigInteger operator + (int a); BigInteger operator - (BigInteger a); BigInteger operator - (int a); BigInteger operator * (BigInteger a); BigInteger operator * (int a); BigInteger operator / (BigInteger a); BigInteger operator / (int a); BigInteger operator % (BigInteger a); int operator % (int a); void operator = (int a); void operator = (BigInteger a); bool operator < (BigInteger a); bool operator < (int a); bool operator <= (BigInteger a); bool operator <= (int a); bool operator > (BigInteger a); bool operator > (int a); bool operator >= (BigInteger a); bool operator >= (int a); bool operator == (BigInteger a); bool operator == (int a);};BigInteger :: BigInteger(){ memset(data, 0, sizeof(data)); positive = true; len = 0;};BigInteger :: BigInteger(char *s){ len = strlen(s); toInt(s);}BigInteger :: BigInteger(int a){ int i; memset(this->data, 0, sizeof(this->data)); if(a<0 this-="">positive = false; else this->positive = true; for(i=0; a; i++) { data[i] = a % 10; a = a / 10; } this->len = i;}void BigInteger :: operator = (int a){ int i; memset(this->data, 0, sizeof(this->data)); if(a<0 this-="">positive = false; else this->positive = true; for(i=0; a; i++) { data[i] = a % 10; a = a / 10; } this->len = i;}void BigInteger :: operator = (BigInteger a){ memset(this->data, 0, sizeof(this->data)); for(int i=0; i<a len="" i="" this-="">data[i] = a.data[i]; } this->positive = a.positive; this->len = a.len;}void BigInteger :: toInt(char *s){ memset(data, 0, sizeof(data)); int i=0, l=len; if(s[i]=='-') {positive = false; i++; len--;} else positive = true; for(int j=0; i<l; i++, j++) { data[j] = s[l - j -1] - '0'; }}void BigInteger :: toStr(char *s){ int j=0; if(!len) s[j++]='0'; if(len && !positive) s[j++]='-'; for(int i=0; i<len i="" s="" j="" data="" len="" -="" i="" -1="" 0="" s="" j="" 0="" istream="" operator="">> (istream &in, BigInteger &a){ char str[maxn]; in >> str; a.len = strlen(str); a.toInt(str); return in;}ostream& operator << (ostream &out, BigInteger &a){ char str[maxn]; a.toStr(str); out << str; return out;}bool BigInteger :: operator < (BigInteger a){ bool positive = true; if(this->positive && !a.positive) return false; else if(!this->positive && a.positive) return true; else if(!this->positive && !a.positive) positive = false; if(this->len < a.len) return positive; else if(this->len > a.len) return !positive; for(int i=len-1; i>=0; i--) { if(data[i]<a data="" i="" return="" positive="" if="" data="" i="">a.data[i]) return !positive; } return false;}bool BigInteger :: operator < (int a){ bool positive = true; if(this->positive && a<0 return="" false="" else="" if="" this-="">positive && a>0) return true; if(!this->positive && a<=0) positive = false; if(len>10) return !positive; else { int n[11], i=0; while(a) { n[i++] = a%10; a /= 10; } if(i > len) return positive; else if(i < len) return !positive; else { for(i=len-1; i>=0; i--) { if(data[i]<n i="" return="" positive="" if="" data="" i="">n[i]) return !positive; } } } return false;}bool BigInteger :: operator <= (BigInteger a){ bool positive = true; if(this->positive && !a.positive) return false; else if(!this->positive && a.positive) return true; else if(!this->positive && !a.positive) positive = false; if(this->len < a.len) return positive; else if(this->len > a.len) return !positive; for(int i=len-1; i>=0; i--) { if(data[i]<a data="" i="" return="" positive="" if="" data="" i="">a.data[i]) return !positive; } return true;}bool BigInteger :: operator <= (int a){ bool positive = true; if(this->positive && a<0 return="" false="" else="" if="" this-="">positive && a>0) return true; if(!this->positive && a<=0) positive = false; if(len>10) return !positive; else { int n[11], i=0; while(a) { n[i++] = a%10; a /= 10; } if(i > len) return positive; else if(i < len) return !positive; else { for(i=len-1; i>=0; i--) { if(data[i]<n i="" return="" positive="" if="" data="" i="">n[i]) return !positive; } } } return true;}bool BigInteger :: operator > (BigInteger a){ bool positive = true; if(this->positive && !a.positive) return true; else if(!this->positive && a.positive) return false; else if(!this->positive && !a.positive) positive = false; if(this->len < a.len) return !positive; else if(this->len > a.len) return positive; for(int i=len-1; i>=0; i--) { if(data[i]<a data="" i="" return="" positive="" if="" data="" i="">a.data[i]) return positive; } return false;}bool BigInteger :: operator > (int a){ bool positive = true; if(this->positive && a<0 return="" true="" else="" if="" this-="">positive && a>0) return false; if(!this->positive && a<=0) positive = false; if(len>10) return positive; else { int n[11], i=0; while(a) { n[i++] = a%10; a /= 10; } if(i > len) return !positive; else if(i < len) return positive; else { for(i=len-1; i>=0; i--) { if(data[i]<n i="" return="" positive="" if="" data="" i="">n[i]) return positive; } } } return false;}bool BigInteger :: operator >= (BigInteger a){ bool positive = true; if(this->positive && !a.positive) return true; else if(!this->positive && a.positive) return false; else if(!this->positive && !a.positive) positive = false; if(this->len < a.len) return !positive; else if(this->len > a.len) return positive; for(int i=len-1; i>=0; i--) { if(data[i]<a data="" i="" return="" positive="" if="" data="" i="">a.data[i]) return positive; } return true;}bool BigInteger :: operator >= (int a){ bool positive = true; if(this->positive && a<0 return="" true="" else="" if="" this-="">positive && a>0) return false; if(!this->positive && a<=0) positive = false; if(len>10) return positive; else { int n[11], i=0; while(a) { n[i++] = a%10; a /= 10; } if(i > len) return !positive; else if(i < len) return positive; else { for(i=len-1; i>=0; i--) { if(data[i]<n i="" return="" positive="" if="" data="" i="">n[i]) return positive; } } } return true;}bool BigInteger :: operator == (BigInteger a){ if(this->positive ^ a.positive) return false; if(this->len != a.len) return false; for(int i=0; i<a len="" i="" if="" this-="">data[i]!=a.data[i]) return false; } return true;}bool BigInteger :: operator == (int a){ if(this->len > 10) return false; if(this->positive ^ a>0) return false; if(a==0 && !this->positive && this->len==1 && !this->data[0]) return true; int j = 0; int n[11] = {0}; while(a) { n[j++] = a%10; a /= 10; } if(this->len != j) return false; else { for(int i = this->len-1, j=0; i>=0; i--, j++) { if(this->data[i]!=n[j]) return false; } } return true;}BigInteger BigInteger :: operator + (BigInteger a){ BigInteger b; if(this->positive && a.positive) { b = (*this).plus(a); } if(!this->positive && !a.positive) { b = (*this).plus(a); b.positive = false; } if(this->positive && !a.positive) { b = (*this).minus(a); } if(!this->positive && a.positive) { b = a.minus(*this); } return b;}BigInteger BigInteger :: operator + (int a){ BigInteger b = a; if(this->positive && b.positive) { b = (*this).plus(b); } if(!this->positive && !b.positive) { b = (*this).plus(b); b.positive = false; } if(this->positive && !b.positive) { b = (*this).minus(b); } if(!this->positive && b.positive) { b = b.minus(*this); } return b;}BigInteger BigInteger :: operator - (BigInteger a){ BigInteger b; if(this->positive && a.positive) { b = (*this).minus(a); //正负根据返回而定，浅拷贝 } if(this->positive && !a.positive) { b = (*this).plus(a); //默认为正数 } if(!this->positive && a.positive) { b = (*this).plus(a); b.positive = false; //负数减正数结果为负 } if(!this->positive && !a.positive) { b = a.minus(*this); } return b;}BigInteger BigInteger :: operator - (int a){ BigInteger b = a; if(this->positive && b.positive) { b = (*this).minus(b); //正负根据返回而定，浅拷贝 return b; } if(this->positive && !b.positive) { b = (*this).plus(b); //默认为正数 return b; } if(!this->positive && b.positive) { b = (*this).plus(b); b.positive = false; //负数减正数结果为负 return b; } if(!this->positive && !b.positive) { b = b.minus(*this); return b; } return b;}BigInteger BigInteger :: plus(BigInteger a){ BigInteger b; int carry=0; for(int i=0; i<=len || i<=a.len; i++) { b.data[i] = data[i] + a.data[i] + carry; carry = b.data[i] / 10; b.data[i] = b.data[i] % 10; } for(b.len=maxn-1; b.len>=0 && !b.data[b.len]; b.len--); b.len++; return b;}BigInteger BigInteger :: minus(BigInteger a){ BigInteger b, *t1 = this, *t2= &a; bool bigger = true, borrow = false; if(*this < a) {bigger = false; t1 = &a; t2 = this;} int n = t1->data[0]; for(int i=0; i<t1->len; i++) { if(n<t2->data[i]) {n = n + 10; borrow = true;} b.data[i] = n - t2->data[i]; if(borrow) {n = t1->data[i+1] - 1; borrow = false;} else n = t1->data[i+1]; } for(b.len=t1->len; b.len>=0 && !b.data[b.len]; b.len--); b.len++; if(!bigger) b.positive = false; return b;}BigInteger BigInteger :: operator * (BigInteger a){ BigInteger b; int n; if((this->positive && !a.positive) || (!this->positive && a.positive)) b.positive=false; for(int i=0; i<this->len; i++) { for(int j=0; j<a len="" j="" n="b.data[i" j="" this-="">data[i] * a.data[j]; b.data[i + j + 1] = b.data[i + j + 1] + n/10; b.data[i + j] = n%10; } } for(b.len=maxn-1; b.len>=0 && !b.data[b.len]; b.len--); b.len++; return b;}BigInteger BigInteger :: operator * (int a){ BigInteger b; int n; if(a<0 b="" positive="!this-">positive; for(int i=0; i<maxn i="" n="b.data[i]" a="" data="" i="" b="" data="" i="" 1="" b="" data="" i="" 1="" n="" 10="" b="" data="" i="" n="" 10="" for="" b="" len="maxn-1;" b="" len="">=0 && !b.data[b.len]; b.len--); b.len++; return b;}BigInteger BigInteger :: operator / (BigInteger a){ BigInteger res, dividend = *this, divisor = a, temp; int m, n; //dividend被除数， divisor除数 if((this->positive && !a.positive) || (!this->positive && a.positive)) res.positive=false; if(this->len < a.len) return res; while(a < dividend || a==dividend) { divisor = a; temp = 1; for(int i=divisor.len; i<dividend.len-1; i++) temp = temp * 10; divisor = divisor * temp; while(divisor < dividend || dividend == divisor) { res = res + temp; dividend = dividend - divisor; } } return res;}BigInteger BigInteger :: operator / (int a){ BigInteger res; int t=0; if(a<0 res="" positive="(!this-">positive); else res.positive = this->positive; for(int i=this->len; i>=0; i--) { t = t * 10+this->data[i]; res.data[i] = t / a; t = t % a; } for(res.len=maxn-1; res.len>=0 && !res.data[res.len]; res.len--); res.len++; return res;}int BigInteger :: operator % (int a){ int t=0; for(int i=this->len; i>=0; i--) { t = t * 10 + this->data[i]; t = t % a; } return t;}BigInteger BigInteger :: operator % (BigInteger a){ BigInteger dividend = *this, divisor = a, temp; //dividend被除数， divisor除数 if(this->len < a.len) return *this; while(a < dividend || a==dividend) { divisor = a; temp = 1; for(int i=divisor.len; i<dividend.len-1; i++) temp = temp * 10; divisor = divisor * temp; while(divisor < dividend || dividend == divisor) { dividend = dividend - divisor; } } return dividend;}</0></maxn></0></a></this-></t2-></t1-></a></n></0></a></n></0></a></n></0></a></n></0></a></len></a></0></0></cstring></iostream>