学步园

写的好搓 先放着

#include<iostream>
#include<string>
#include<cstring>
using namespace std;
string jianfa(string a,string b,char f)
{
	if(a.compare(b)==0)
	{	
		string c="0";
		return c;
	}
		
	string c="",ans="",t;
	int  flag=0,k=0;//flag退位的标志
	int flag2;//结果正负的标志
	if(f=='+')
		flag2=0;
	else
		flag2=1;
	if(a.length()<b.length()||(a.length()==b.length()&& a.compare(b)<0))
	{
		t=a;
		a=b;
		b=t;
		flag2^=1;
	}
	int i=a.length()-1,j=b.length()-1;
	while(i>=0&&j>=0)
	{
		if(a[i]+flag>b[j])
		{
			c+=a[i]+flag-b[j]+'0';
			flag=0;
		}
		else if (a[i]+flag==b[j])
		{
			c+='0';
			flag=0;
		}
		else
		{
			c+=(a[i]-'0')+flag+10-(b[j]-'0')+'0';
			flag=-1;
		}
		i--;j--;k++;
	}
	int len=k-1;
	while(c[len]=='0'&&len>0)
		len--;//检索高位
	for(j=0;j<=len;j++)
		ans+=c[j];
	if(flag2)
	{ 
		ans+='-';
	}//结果正负判断
	char tt;
	for(i=0,j=ans.length()-1;i<j;i++,j--)//倒置
	{
		tt=ans[i];
		ans[i]=ans[j];
		ans[j]=tt;
	}
	return ans;
}

int main()
{
	string a,b;
	while(cin>>a>>b&&(a[0]!='0'||b[0]!='0'))
	{
		string s1(a.begin()+1,a.end());
		string s2(b.begin()+1,b.end());
		if(a[0]==b[0])
		{
			cout<<jianfa(s1,s2,a[0])<<endl;
		}
		else
		{
			int num1[150],num2[150];
			int ans[150];
			memset(ans,0,sizeof(ans));
			memset(num1,0,sizeof(num1));
			memset(num2,0,sizeof(num2));
			int l1=s1.size(),l2=s2.size();
			int i,j;
			for(i=l1-1,j=0;i>=0;i--,j++)
				num1[j]=s1[i]-'0';
			for(i=l2-1,j=0;i>=0;i--,j++)
				num2[j]=s2[i]-'0';
			int max=l1>l2?l1:l2;
			for(i=0;i<max;i++)
			{
				ans[i]+=num1[i]+num2[i];
				if(ans[i]>9)
				{
					ans[i+1]+=ans[i]/10;
					ans[i]=ans[i]%10;
				}
			}
			if(b[0]=='+')
				cout<<"-";
			int flag=1;
			for(i=max+1;i>=0;i--)
				if(flag&&ans[i]==0)
					continue;
				else
				{
					flag=0;
					cout<<ans[i];
				}
			cout<<endl;
		}	
	}
	return 0;
}