大数减法 模板

#include<iostream>
#include<stdio.h>
#include<math.h>
#include<string.h>
using namespace std;

int main()
{
    char a[1005];
    char b[1005];
    int aa[1005];
    int bb[1005];
    int c[1005];

    while(~scanf("%s%s",a,b))
    {

        memset(aa,0,sizeof(aa));
        memset(bb,0,sizeof(bb));
        int lena = strlen(a);
        int lenb = strlen(b);


        int sign = 0;  //用于判断正负数

        if( (lenb > lena ) || (lena == lenb && strcmp(b,a) > 0))
        {
            sign = 1;
            swap(a,b);
        }

        for(int i = lena - 1; i >= 0; i--)
        {
            aa[lena - i -1] = a[i] - ‘0‘;
        }

        for(int i = lenb - 1; i >= 0; i--)
        {
            bb[lenb - i -1] = b[i] - ‘0‘;
        }

        int lenc = lena > lenb ? lena : lenb;

        int jiewei = 0 ;
        for(int i = 0 ; i < lenc ; i++)
        {
            if(aa[i] - bb[i] +jiewei < 0)
            {
                c[i] = aa[i] - bb[i] + jiewei +10;
                jiewei = -1;
            }
            else
            {
                c[i] = aa[i] - bb[i] +jiewei;
                jiewei = 0;
            }
        }

        while(c[lenc-1] == 0 && lenc > 1)
            {
                lenc--;
            }
        if(sign == 1)
            printf("-");
        for(int i = 0; i < lenc; i++)
        {
            printf("%d",c[i]);
        }
        puts("");
    }

    return 0;
}