大数运算（C++类实现）
#include<cstdio>#include<iostream>using namespace std;const int maxn = 200;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 = (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; } string str() const { string res = ""; for(int i = 0; i < len; i++) res = (char)(s[i] + '0') + res; if(res == "") res = "0"; return res; } 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; } 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-1; i++){ c.s[i+1] += c.s[i] / 10; c.s[i] %= 10; } c.clean(); return c; } bign operator - (const bign& b) { bign c; c.len = 0; for(int i = 0, g = 0; i < len; i++) { int x = s[i] - g; if(i < b.len) x -= b.s[i]; if(x >= 0) g = 0; else { g = 1; x += 10; } c.s[c.len++] = x; } c.clean(); return c; } bool operator < (const bign& b) const{ 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) const{ return b < *this; } bool operator <= (const bign& b) { return !(b > *this); } bool operator == (const bign& b) { return !(b < *this) && !(*this < b); } bign operator += (const bign& b) { *this = *this + b; return *this; }};istream& operator >> (istream &in, bign& x) { string s; in >> s; x = s.c_str(); return in;}ostream& operator << (ostream &out, const bign& x) { out << x.str(); return out;}int main() { bign a, b; cin >> a >> b; a += b; cout << a << endl; return 0;}