单个字符逐个读入的时候如何判断到达文件末尾？

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;

char s[200];

inline int input(char *s)
{
 ``   int i;
    *s = getchar();
    for(i=1; *(s + i) != ‘\n‘ && *(s + i) != EOF; i++)
        *(s + i) = getchar();
    int j = *(s + i) != EOF ? 1 : 0;
    *(s + i) = ‘\0‘;
    return j;
}

char random()
{
    int r = rand()%3;
    char c;
    if(r == 0)
        c = rand()%10 + ‘0‘;
    else if(r == 1)
        c = rand()%26 + ‘A‘;
    else
        c = rand()%26 + ‘a‘;
    return c;
}

int main()
{

    freopen("out.txt","r",stdin);
    while(input(s));
    printf("%s\n",s);

//    srand(time(0));
//    freopen("out.txt","w",stdout);
//    int n = 20;
//    for(int i=0; i<n; i++)
//    {
//        printf("%c",random());
//    }

    return 0;
}