AOJ 435 带小数高精度

以前没写过带小数的高精度，这题仅仅要求实现加法，我依旧写的做很挫，还WA了两次。

注意求和之后去除后缀的无用0

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>

#define max(a,b) (((a)>(b))?(a):(b))

using namespace std;

class bign {
    public:
        int id[1000],sd[1000],ilen,slen;
        bign():ilen(0),slen(0) {
            memset(id,0,sizeof(id));
            memset(sd,0,sizeof(sd));
        };
        bign(char *num) {
            memset(id,0,sizeof(id));
            memset(sd,0,sizeof(sd));
            while(num[0] == '0') num++;
            if(num[0] == '.') num--;
            int len = strlen(num),ppos = 0;
            while(num[ppos] != '.') ppos++;
            while(num[len - 1] == '0') len--;
            if(num[len - 1] == '.') len++;
            for(int i = ppos - 1;i >= 0;i--) id[ppos - i - 1] = num[i] - '0';
            for(int i = ppos + 1;i < len;i++) sd[i - ppos - 1] = num[i] - '0';
            ilen = ppos; slen = len - ppos - 1;
        };
        string str() {
            char out[1000];
            int pos = 0;
            for(int i = ilen - 1;i >= 0;i--) out[pos++] = id[i] + '0';
            out[pos++] = '.';
            for(int i = 0;i < slen;i++) out[pos++] = sd[i] + '0';
            out[pos] = 0;
            return string(out);
        }
};

bign operator+(bign a,bign b) {
    int len = max(a.slen,b.slen);
    for(int i = len - 1;i >= 0;i--) {
        a.sd[i] += b.sd[i];
        if(i && a.sd[i] > 9) {
            a.sd[i - 1] += a.sd[i] / 10;
            a.sd[i] %= 10;
        }
    }
    if(a.sd[0] > 9) {
        a.id[0]++;
        a.sd[0] %= 10;
    }
    for(a.slen = len;a.sd[a.slen - 1] == 0 && a.slen > 1;a.slen--);
    len = max(a.ilen,b.ilen);
    for(int i = 0;i < len;i++) {
        a.id[i] += b.id[i];
        a.id[i + 1] += a.id[i] / 10;
        a.id[i] %= 10;
    }
    if(a.id[len]) a.ilen = len + 1;
    else a.ilen = len;
    return a;
}

int main() {
    char a[1000],b[1000];
    while(~scanf("%s%s",a,b)) {
        bign ga(a),gb(b);
        cout << (ga + gb).str() << endl;
    }
    return 0;
}