利用顺序表实现大整数相减的主要算法该怎么写

只找到了相加如下
LongInt Add(LongInt A, LongInt B)
{
int flag = 0,i = 0,n,m;
LongInt C;
n = A.length;
m = B.length;
while (i<n&&i<m)
{
C.data[i] = (A.data[i] + B.data[i] + flag) % 10;
flag = (A.data[i] + B.data[i] + flag) / 10;
i++;
}
for (; i < n; i++)
{
C.data[i] = (A.data[i] + flag) % 10;
flag = (A.data[i] + flag) / 10;
}
for (; i < m; i++)
{
C.data[i] = (B.data[i] + flag) % 10;
flag = (B.data[i] + flag) / 10;
}
C.length = max(m, n) + flag;
if (flag == 1)
C.data[C.length - 1] = 1;
return C;
}
求助相减应该怎么写

https://blog.csdn.net/hingcheung/article/details/70249790