高精度基础之减法格式1

#include<bits/stdc++.h>
using namespace std;
int main(void)  {
string s1,s2;
cin>>s1>>s2;
int a[505],b[505];
memset(a,0,sizeof(a));
memset(b,0,sizeof(b));
int len1=s1.length();
int len2=s2.length();
//关键！
    if((len1<len2)||(len1==len2&&s1<s2)) {
       string tmp;
       tmp=s1;
       s1=s2;
       s2=tmp;
       printf("-");
    }
    for(int i=0;i<len1;i++) a[i]=s1[len1-i-1]-'0';
    for(int i=0;i<len2;i++) b[i]=s2[len2-i-1]-'0';
    for(int i=0;i<len1;i++) {
        a[i]-=b[i];
        if(a[i]<0) {a[i]+=10;a[i+1]--;}
    }
    while(a[len1-1]==0&&len1>=2) len1--;
    for(int i=len1-1;i>=0;i--)
        printf("%d",a[i]);
    printf("\n");
 return 0;
}