fgetc（）在函数中无法正常工作

Question

I am trying to read a text file, character by character, with fgetc() function but it does not show any output. It is a school project and it is still in very very simple way just to test the functionality of the program.

#include <stdio.h>
#include <stdlib.h>

void fn1(FILE *f);
void fn9(FILE *fp, char, char);

int main() {
  FILE *fp = fopen("text.txt", "r");
  if (fp == NULL) {
    perror("Error: ");
    exit(1);
  }
  fn1(fp);
  fn9(fp, '0', '9');

  fclose(fp);
  return 0;
}

void fn1(FILE *f) {
  int num, sum = 0, count = 0;

  while (fscanf(f, "%d", &num) == 1) {
    if (num > 0) {
      sum += num;
      count++;
    }
  }
  printf("the avg of positive nums is %.2f", (float) sum / count);
}

void fn9(FILE *fp, char m, char n) {
  int ch;
  int count1 = 0, count2 = 0;

  while ((ch = fgetc(fp)) != EOF) {
    if (ch == m)
      count1++;
    if (ch == n)
      count2++;
    printf("%c", ch);
    if (ferror(fp))
      break;
  }

  printf("\n%c is seen %d times", m, count1);
  printf("\n%c is seen %d times", n, count2);

  fclose(fp);
}

The file's content that I test is:

      90
      16
      -34
      100

Answer 1

After fn(fp) return, fp will point to the last location in the file. It needs to be reset to the start of file before fn9 is called. Use fseek to point fp to the start of file and it should work :)