C++大数运算与运算符重载
#include <iostream> #include <cstring> using namespace std; class BigNum { private: char *num; int length; public : BigNum(); BigNum(const char *); BigNum(const BigNum & bigNum); int print(); BigNum operator + (BigNum); BigNum & operator =(BigNum); }; BigNum & BigNum::operator = (BigNum bigNum) { this->length=bigNum.length; delete this->num; this->num=new char[this->length+1]; for(int i=0;i<this->length;i++) { this->num[i]=bigNum.num[i]; } this->num[length]='\0'; return *this; } BigNum::BigNum() { this->length=0; } BigNum::BigNum(const char *bigNum) { this->length=strlen(bigNum); num=new char[length+1]; for(int i=0;i<length;i++) { this->num[i]=bigNum[length-1-i]; } } BigNum::BigNum(const BigNum & bigNum) { this->length=bigNum.length; this->num=new char[this->length+1]; for(int i=0;i<this->length;i++) { this->num[i]=bigNum.num[i]; } this->num[length]='\0'; } int BigNum::print() { for(int i=length-1;i>=0;i--) cout<<this->num[i]; return this->length; } BigNum BigNum::operator + (BigNum bigNum) { char * a; int length=max(this->length,bigNum.length); a=new char[length+2]; int car=0; int i; for(i=0;i<length||car!=0;i++) { car=this->num[i]-'0'+bigNum.num[i]-'0'+car; a[i]=car%10+'0'; car/=10; } a[i]='\0'; delete this->num; this->num=a; return *this; } int main() { BigNum bigNum_1("123456"); BigNum bigNum_2(bigNum_1); bigNum_1.print(); cout<<endl; bigNum_2.print(); cout<<endl; bigNum_1=bigNum_2+bigNum_1; bigNum_1.print(); return 0; }
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