有人可以帮我找出为什么没有输出吗？

Question

#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main(void) {
   char str[50];
   int count[26] = {0};
   int x;
   int len;
   int max;

printf("Enter your input: ");
scanf("%s", str);

while( ! feof(stdin)) {
  len = strlen(str);
  for(x = 0; x < len; ++x) {
    char ch = str[x];
    int sub = ch - 97;
    count[sub] = count[sub] + 1;
  }
  scanf("%s", str);
}
max = count[0];
for(x = 0; x < len; ++x) {
    if(count[x] > max){
      max = count[x];
    }
}

printf("Missing letters: ");
for(x = 0; x < 26; ++x) {
  if(count[x] == 0) {
    x = x + 97;
    printf("%c", x);
  }
}
printf("\n");
return 0;
}

I'm new to C and I've been trying to fix this for a few hours now and I'm just not understanding. I think the issue is with the while loop, but I've just started coding I have no idea. Does anything jump out at anyone? This is supposed to read a sentence and output the letters that were not seen . Thank you.

Answer 1

Your while loop only terminates when there is an EOF. Use Ctrl^D to send the EOF signal to escape the feof function.