Can you tell me what's wrong with my code, I cheked more than 10 times, may be something wrong with input?
#include <vector>
#include <string>
#include <stdio.h>
#include <iostream>
using namespace std;
int main()
{
    char s[1000];
    //string s;
    int i=0;
    char c;
    bool sign=true;
    gets(s);
    while (!EOF)
    {
        i=0;
        while (s[i]!='\0')
        {
            if (s[i]=='.'||s[i]=='!'||s[i]=='?') sign=true;
            if (s[i]>='A'&&s[i]<='Z'&&sign) {sign=false;}
            else if (s[i]>='A'&&s[i]<='Z') s[i]=tolower(s[i]);
            cout << s[i];
            i++;
        }
        gets(s);
    }
    return 0;
}