SPOJ question - WHat is going wrong here?

I was answering this spoj question: http://www.spoj.pl/problems/JAVAC/

I coded the submission in C++. I am pasting it below. The submission consistently gives wrong answer. I cannot find a test case for which it will fail. Can anyone help me out ?

Thanks very much.

#include<iostream>
#include<string>
#include<algorithm>

using namespace std;

char *ans;

bool iscapital(char c)
{
  if(c >='A' && c <='Z')
    return true;
  else
    return false;
}

string translate(string current)
{ 
  ans = new char[2*current.length() + 1];
  int jflag = 0, cflag = 0,j = 0, i = 0;

  if(iscapital(current[0]))
  {
    return "Error!";
  }

  while(i < current.length())
  {
    if(current[i] !='_')
    {
      if(!(current[i] >= 'A' && current[i] <= 'Z'))
      {
    ans[j] = current[i];
    i++;
    j++;
      }
    }

    if(current[i] == '_')
    {
      if(jflag == 1)
    return "Error!";

      cflag = 1;
      i++;
      if(i < current.length())
      {
    //convert to capital
    if(iscapital(current[i]))
      return "Error!";

    ans[j] = (char)((int)current[i] - 32);
    i++;
    j++;
      }
    }

    if(iscapital(current[i]))
    {
      if(cflag == 1)
    return "Error!";

      jflag = 1;

      ans[j] = '_';
      j++;
      ans[j] = (char)((int)current[i] + 32);
      j++;
      i++;
    }
  }
  ans[j] = '\0';
  string ret = ans;
  return ret;
}



int main()
{

  string current;

  while(cin>>current)
  {
    c开发者_高级运维out<<translate(current)<<endl;
  }
  return 0;
}

I haven't tried it (never used SPOJ), but could it be possible that there are other invalid formats? E.g.:

123asd

_asd

asd___a

I am messing with your code now, see if I can make it works. Good luck!

EDIT: Passed! Try add the following:

1. Detect error when first or last letter is '_'

2. Detect if there are consecutive '_'s (e.g., 'a__b')

3. Detect other characters (e.g., 'adq21#')

All the three cases here should be errors. Cheers!