Thread: Files problem

main() is usually declared as returning an integer. When main() exits, it should specify a return code. If your input file does not open properly, it should probably exit too, instead of falling through to your fscanf().

Todd

thats what my if statement would display though if the file was opened or not. but its goes through and displays whats in the hours variable which is the bottom printf.

See this online reference: http://www.cppreference.com/stdio/fscanf.html

What is fscanf() returning?

A integer number from the payrates.dat file.

Wrong answer. Put some error checking into your program and repost. Test the return value of fscanf please.

I get a minus 1 (-1)

Code:

#include <stdio.h>

main() {
       FILE *fp;
       int hour, check;
       
fp   = fopen("payrates.dat", "r");  /* input file - read mode */
  if (fp == NULL)
  {
    printf("input file not opened");
    
  }
  
  check = fscanf(fp, "&#37;d\n", hour);
  fclose(fp);
  printf("%d", check);
}

It's not clear from what I'm seeing whether your file is opening correctly. Is it?

Also: just like scanf, fscanf takes its argument by address, not by value. If your file is opening correctly and not empty, this is almost certainly your difficulty here.

Ya, i dont think it is because i added a fprint to see if i can print soemthing into the file and it doesn't

Code:

#include <stdio.h>

main() {
       FILE *fp;
       int hour, check;
       char line[56];
       
  fp = fopen("payrates.dat", "a");  /* input file - read mode */
  if (fp == NULL)
  {
    printf("input file not opened");
    
  }
  printf("Enter a line: ");
  gets(line);
  fprintf(fp,"&#37;s\n", line);
  check = fscanf(fp, "%d\n", hour);
  fclose(fp);
  printf("%d", check);
}

Originally Posted by bigmac(rexdale)

Ya, i dont think it is because i added a fprint to see if i can print soemthing into the file and it doesn't

Well, you should know. Does the line "input file not opened" print? If so, it didn't open. If not, then it did.

Can you find a "payrates.dat" file in your directory, somewhere? Is your program ending abnormally? (My copy of your program did, because I ignored the compiler warning about line 17.) If so, the output might not get written before the crash. Fix line 17 (you need an ampersand in front of hour) and see what happens.