重载运算符加减乘除170312

#include <cstdio>
#include <cstring>
//2017.3.12
int max(int a,int b){return a >= b ? a : b;}
struct bignum{
    int data[1001],len;
    bignum(){len = 1;memset(data,0,sizeof(data));}
};
void operator==(bignum &a,int b){ 
    int t,i = 0;
    int tmp[1001];
    while(b > 0){
        i++;
        t = b % 10;
        tmp[i] = t;
        b = (b - t) / 10;
    }
    for(int j = 1;j <= i;j++){
        a.data[j] = tmp[j];
    }
    a.len = i;
}
bignum operator-(bignum a,bignum b){
    bignum c;
    c.len = max(a.len,b.len);
    for(int i = 1;i <= c.len;i++){
        if(a.data[i] < b.data[i])
            a.data[i] += 10,a.data[i + 1]--;
        c.data[i] = a.data[i] - b.data[i];
    }
    if(c.data[c.len] == 0)c.len--;
    return c;
}
void operator-=(bignum &a,bignum b){
    a = a - b;
}
bignum operator/(bignum a,int b){
    int d = 0;
    for(int i = a.len;i >= 1;i--) 
    {
        d = d * 10 + a.data[i]; 
        a.data[i] = d / b;
        d = d % b; 
    }
    while(a.data[a.len] == 0 && a.len > 1) a.len--; 
    return a;
}
void operator/=(bignum &a,int b){
    a = a / b;
}
bignum operator+(bignum a,bignum b){
    bignum c;
    c.len = max(a.len,b.len);
    for(int i = 1;i <= c.len;i++){
        c.data[i] += a.data[i] + b.data[i];
        if(c.data[i] >= 10){
            c.data[i] %= 10;
            c.data[i + 1]++;
        }
    }
    if(c.data[c.len + 1] > 0)c.len++;
    return c;
}
void operator+=(bignum &a,bignum b){
    a = a + b;
}
bignum operator*(bignum a,bignum b){
    bignum c;
    c.len = a.len + b.len;
    for(int i = 1;i <= a.len;i++){
        for(int j = 1;j <= b.len;j++){
            c.data[i+j-1] += a.data[i] * b.data[j];
            if(c.data[i+j-1] >= 10){
                c.data[i+j] += c.data[i+j-1] / 10;
                c.data[i+j-1] %= 10;
            }
        }
    }
    if(c.data[c.len] == 0)c.len--;
    return c;
}
void operator*=(bignum &a,bignum b){
    a = a * b;
}
void get(bignum &a){
    char x[10001];
    scanf("%s",x + 1);a.len = strlen(x + 1);
    for(int i = 1;i <= a.len;i++){
        a.data[a.len - i + 1] = x[i] - '0';
    }
}
void put(bignum a){
    for(int i = a.len;i >= 1;i--)
        printf("%d",a.data[i]);
}