fgets is getting skipped

Question

I have little program where I want to ask for an option and then for a filename.

  //Some code before
   printf(\"######################\\n\");
   printf(\"# 1.          


        

Answer 1

fget() is not getting skipped but reads the left over new-line from the previous input using getchar().

It is all about complete error checking and sane logging:

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


#define LINE_LEN (1024)


int main(void)
{
  int action = 0;
  char input[LINE_LEN] = {0};
  size_t len = 0;

  printf("enter decision: ");
  {
    int c = fgetc(stdin); /* equivalent to getchar() */
    if (EOF == c)
    {
      putc('\n');

      if (ferror(stdin))
      {
        perror("fgetc(stdin) failed");
      }
      else
      {
        fprintf(stderr, "read EOF, aborting ...\n");
      }

      exit(EXIT_FAILURE);
    }

    action = c;
  }

  /* read left over from previous input: */
  {
    int c = fgetc(stdin);
    if (EOF == c)
    {
      putc('\n');

      if (ferror(stdin))
      {
        perror("fgetc(stdin) failed");
        exit(EXIT_FAILURE);
      }
    }
    else if ('\n' != c)
    {
      fprintf(stderr, "read unexpected input (%d), aborting ...\n", c);
      exit(EXIT_FAILURE);
    }
  }

  len = strlen(input);
  if (LINE_LEN <= len + 1) 
  {
    fprintf(stderr, "input buffer full, aborting ...\n");
    exit(EXIT_FAILURE);
  }

  switch(action - '0')
  {
    case 1:
      printf("enter file name: ");
      if (NULL == fgets(input + len, LINE_LEN - len, stdin))
      {
        putc('\n');

        if (ferror(stdin))
        {
          perror("fgets() failed");
        }
        else
        {
          fprintf(stderr, "missing input, aborting ...\n");
        }

        exit(EXIT_FAILURE);
      }

      (input + len)[strcspn(input + len, "\n")] = '\0'; /* cut off new-line, if any. */

      printf("read file name '%s'\n", input + len);

      break;

    default:
      fprintf(stderr, "unknown action (%d), aborting ...\n", action);
      exit(EXIT_FAILURE);

      break;
  }
}