大数的四则运算c++

以下是C++实现大数的四则运算的两个例子：

1. 大数相加

bign add(bign a, bign b) {
    bign c;
    int carry = 0; // 进位
    for (int i = 0; i < a.len || i < b.len; i++) {
        int temp = a.d[i] + b.d[i] + carry;
        c.d[c.len++] = temp % 10;
        carry = temp / 10;
    }
    if (carry != 0) {
        c.d[c.len++] = carry; // 如果最后一位的进位不为0，直接赋给结果的最高位
    }
    return c;
}

2. 大数乘以一个整数

bign multi(bign a, int b) {
    bign c;
    int carry = 0;
    for (int i = 0; i < a.len; i++) {
        int temp = a.d[i] * b + carry;
        c.d[c.len++] = temp % 10;
        carry = temp / 10;
    }
    while (carry != 0) {
        c.d[c.len++] = carry % 10;
        carry /= 10;
    }
    return c;
}