四则运算

#include <bits/stdc++.h>
using namespace std;
int main()
{
string CALCNUM;
string NUMFIRST,NUMSECOND;
int NUMFIRSTINT[100],NUMSECONDINT[100];
getline(cin,CALCNUM);
for(int i=0;i<CALCNUM.size();i++)
{
if(CALCNUM[i]=='+')
{
NUMFIRST=CALCNUM.substr(0,i-1);
NUMSECOND=CALCNUM.substr(i+1,CALCNUM.size()-1);
}
}
for(int i=0;i<NUMFIRST.size();i++)
{
NUMFIRSTINT[100]=NUMFIRST[i]-'0';
}
for(int i=0;i<NUMSECOND.size();i++)
{
NUMSECONDINT[100]=NUMSECOND[i]-'0';
}
int LENNUMFIRSTINTNUMSECONDINT=max(NUMFIRST.size(),NUMSECOND.size());
int NUMTHIRDINT[1000];
for(int i = 0 ; i < LENNUMFIRSTINTNUMSECONDINT ; i++)
{
NUMTHIRDINT[i]=NUMFIRSTINT[i]+NUMTHIRDINT[i]+NUMSECONDINT[i];
NUMTHIRDINT[i+1]=NUMTHIRDINT[i]/10;
NUMTHIRDINT[i]=NUMTHIRDINT[i]%10;
}
for(int i=LENNUMFIRSTINTNUMSECONDINT;i>0;i--){
cout<<NUMTHIRDINT[i];
}
return 0;
}