bign类C++高精度模板

很不错的高精度模板，但这个模板只能算加、减、乘运算，而且操作减法的时候只能大数减小数，由于个人认为除法用的不太多，于是就不添加除法啦，所以最重要的操作是 + 、 +=、*、*=、-=、==，这些基本的运算。

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <string>#include <algorithm>using namespace std;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){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; i < max(len, b.len); i++){c.s[i] += s[i]-b.s[i];if(c.s[i] < 0){c.s[i] += 10;c.s[i+1]--;}}c.clean();c.len = len;return c;}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, bign &x){out << x.str();return out;}int main(){bign a, b, c, d, e;while(cin>>a>>b){c = a+b;d = a-b;e = a*b;cout<<"a+b"<<"="<<c<<endl;cout<<"a-b"<<"="<<d<<endl;cout<<"a*b"<<"="<<e<<endl;if(a != b) printf("YES\n");else printf("NO\n");}return 0;}