JAVAC - Java vs C ++.cpp

#include<bits/stdc++.h>

using namespace std;

int main(void)
{
    char s[500]= {},res[500]= {};

    while(scanf("%s",s)!=EOF)
    {
        int index=0,status = 0,cplus=0,java=0;
        int l=strlen(s);
        for(int i=0; i<l; i++)
        {
            if(i==0 && ((s[i]=='_')||((s[i]>=65)&&(s[i]<=90))))
            {
                status = 1;
                break;
            }
            else if(i==(l-1) && (s[i]=='_'))
            {
                status = 1;
                break;
            }
            else if(s[i]>=65 && s[i]<=90)
            {
                if(cplus)
                {
                    status = 1;
                    break;
                }
                java=1;
                res[index++]='_';
                res[index++]=s[i]+32;
            }
            else if(s[i]=='_')
            {
                i++;
                cplus = 1;
                if(java)
                {
                    status = 1;
                    break;
                }
                if(s[i]>=97 && s[i]<=122)
                {
                    res[index++]=s[i]-32;
                }
                else
                {
                    status=1;
                    break;
                }
            }
            else
                res[index++]=s[i];
        }
        res[index]='\0';
        if(status == 0)
            printf("%s\n",res);
        else
            printf("Error!\n");
    }
    return 0;
}