重载运算符
vivarock
2018-01-04 13:11:53
```cpp
#include<iostream>
#include<cstdio>
#include<cstring>
#define N 2002
using namespace std;
struct Bignum{
int len,s[N];
bool f;//1正，0负
Bignum() {
len = 1;
memset(s,0,sizeof(s));
f = 1;
}
// =
Bignum operator = (const char * num) {
len = strlen(num);
if(num[0] == '-') {
f = 0;
for(int i=1;i<len;i++)
s[len-i] = s[i] - 48;
len--;
}
else {
for(int i=0;i<len;i++)
s[len-i] = num[i] - 48;
}
return * this;
}
Bignum operator = (const int num) {
char a[N];
sprintf(a,"%d",num);
* this = a;
return * this;
}
// 初始化
Bignum(const char * num) {
* this = num;
}
Bignum(const int num) {
* this = num;
}
// 逻辑运算符
bool operator < (const Bignum & x) const {
if(len != x.len) return len < x.len;
for(int i=len;i>0;i--)
if(s[i] != x.s[i])
return s[i] < x.s[i];
return false;
}
bool operator > (const Bignum & x) const {return x < * this;}
bool operator <= (const Bignum & x) const {return !(x < * this);}
bool operator >= (const Bignum & x) const {return !(* this < x);}
bool operator == (const Bignum & x) const {return !(* this < x or x < * this);}
bool operator != (const Bignum & x) const {return * this < x or x < * this;}
// + and +=
Bignum operator + (const Bignum & x) {
Bignum ans,xx = x;
if(f == 1 and xx.f == 0) {//正数加负数等于正数减去正数
f = 1;
xx.f = 1;
ans = * this - xx;
return ans;
}
if(f == 0 and xx.f == 0) {//负数加负数等于负的两数绝对值之和
f = 1;
xx.f = 1;
ans = * this + xx;
return ans;
}
if(f == 0 and xx.f == 1) {//负数加正数等于后面的数减去前面的数的绝对值
f = 1;
xx.f = 1;
ans = xx - * this;
return ans;
}
ans.len = max(len,x.len) + 1;
int k = 0;
for(int i=1;i<=ans.len;i++) {
ans.s[i] = s[i] + x.s[i] + k;
k = ans.s[i] / 10;
ans.s[i] %= 10;
}
if(ans.s[ans.len] == 0)
ans.len--;
return ans;
}
Bignum operator += (const Bignum & x) {
* this = * this + x;
return * this;
}
// - and -=
Bignum operator - (const Bignum & x) {
Bignum ans,xx = x;
ans.len = 1;
if(f == 1 and xx.f == 1) {//两个正数的差
if(* this < x) {
ans.f = 0;
while(ans.len <= len or ans.len <= xx.len) {
if(xx.s[ans.len] < s[ans.len]) {
xx.s[ans.len] += 10;
xx.s[ans.len+1]--;
}
ans.s[ans.len] = xx.s[ans.len] - s[ans.len];
ans.len++;
}
}
if(* this == x)
return ans;
if(* this > x) {
ans.f = 1;
while(ans.len <= len or ans.len <= xx.len) {
if(s[ans.len] < xx.s[ans.len]) {
s[ans.len] += 10;
s[ans.len+1]--;
}
ans.s[ans.len] = s[ans.len] - xx.s[ans.len];
ans.len++;
}
}
while(ans.len > 0 and ans.s[ans.len] == 0)
ans.len--;
return ans;
}
else if(f == 1 and xx.f == 0) {//被减数为正，减数为负，相当于两数绝对值之和
ans.f = 1;
xx.f = 1;
ans = * this + xx;
return ans;
}
else if(f == 0 and xx.f == 1) {//被减数为负，减数为正，相当于负的两数绝对值之和
ans.f = 0;
f = 1;
ans = * this + xx;
return ans;
}
else if(f == 0 and xx.f == 0) {//被减数为负，减数为负，相当于负的减数减去被减数
f = 1;
xx.f = 1;
ans = xx - * this;
return ans;
}
}
Bignum operator -= (const Bignum & x) {
* this = * this - x;
return * this;
}
// * and *=
Bignum operator * (const Bignum & x) {
Bignum ans,xx = x;
if((f == 1 and xx.f == 1) or (f == 0 and xx.f == 0))//同号为正
ans.f = 1;
else ans.f = 0;//异号为负
for(int i=1;i<=len;i++) {
int x = 0;
for(int j=1;j<=xx.len;j++) {
ans.s[i+j-1] += s[i] * xx.s[j] + x;
x = ans.s[i+j-1] / 10;
ans.s[i+j-1] %= 10;
}
ans.s[i+xx.len] = x;
}
ans.len = len + xx.len;
while(ans.s[ans.len] == 0 and ans.len > 1)
ans.len--;
return ans;
}
Bignum operator *= (const Bignum & x) {
* this = * this * x;
return * this;
}
// / and /=
Bignum numcpy(Bignum & x,Bignum & y,int det) {
for(int i=1;i<=x.len;i++)
y.s[det+i-1] = x.s[i];
y.len = x.len + det - 1;
}
Bignum operator / (const Bignum & x) {
Bignum ans,temp,xx = x;
if((* this == temp) or (* this < xx))//不够除或是被除数为0，直接返回0
return temp;
else {
if((f == 1 and xx.f == 1) or (f == 0 and xx.f == 0))//同号为正
ans.f = 1;
else ans.f = 0;//异号为负
xx.f = 1;//极为重要，被这个卡了一下午，下面的减法是最简单的减法，所以要把两个数都变成正数
f = 1;//同上
ans.len = len - xx.len + 1;
for(int i=ans.len;i>0;i--) {
memset(temp.s,0,sizeof(temp.s));
numcpy(xx,temp,i);
while(* this >= temp) {
* this -= temp;
ans.s[i]++;
}
}
while(ans.len > 0 and ans.s[ans.len] == 0)
ans.len--;
return ans;
}
}
Bignum operator /= (const Bignum & x) {
* this = * this / x;
return * this;
}
// over
};
ostream & operator << (ostream & out,const Bignum & x) {
if(x.f == 0) cout<<"-";
for(int i=x.len;i>0;i--)
cout<<x.s[i];
return out;
}
istream & operator >> (istream & in,Bignum & x) {
char num[N];
in>>num;
x = num;
return in;
}
int main()
{
Bignum x,y;
cin>>x>>y;
x *= y;
cout<<x;
return 0;
}
```