Help with struct... not returning correct results.

This is the code I have. To check my struct I put in a printf function and instead of returning
M 60 2
F 42 1
F 12 4
M 26 3

it's returning
F 12 4
1986850018 8M 26 3
0 0

Code:

---

#include <stdio.h>
#define MAXRECORDS 4

struct record
{
  char gender;
  int age;
  int lead;
};

void read_file();

int main()
{
  read_file();
}

void read_file()
{
  FILE *fpin;
  int i;
  struct record rec[MAXRECORDS];

  fpin = fopen("custsurvey.dat", "r");

  if(fpin == NULL)
  {
      printf("Error opening file");
  }
  else
  {
      while(!feof(fpin))
      {
        for(i = 0; i < MAXRECORDS; i++)
            fscanf(fpin, "%c  %d %d", &rec[i].gender, &rec[i].age, &rec[i].lead);
      }
  }
  for(i = 0; i < MAXRECORDS; i++)
      printf("%c  %d %d", rec[i].gender, rec[i].age, rec[i].lead);

  fclose(fpin);
}

---

You've got a for loop inside your while loop; so you'll read 0,1,2,3; and then if feof is false (which it is) you'll do it again, so you'll read 0, 1, 2, 3 and overwrite. (As you've noticed, every other read is going wrong, probably because it's reading ... something in for %c and then not matching either of the %d's, which means they get garbage values. In this case, "something" might be a new-line or carriage-return character.)

Edit: Oh, forgot to mention: feof will be false the first time through even if you were reading correctly, because feof doesn't get set to true until you try to read more data that isn't there. Also, the reason we believe your %c is picking up a new line is that new lines were printed in your output, despite the fact that they don't appear in your program.

Ok how would I stop it reading in the newline character?

Put a space in your format string before the %c. (Perhaps contrary to expectations, and perhaps contrary to everything else, spaces don't literally match spaces in your input. Any whitespace in a format string causes *scanf to ignore whitespace before reading the next conversion.)

Awesome thanks, work's now :-)

Quote:

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Originally Posted by tabstop

Put a space in your format string before the %c. (Perhaps contrary to expectations, and perhaps contrary to everything else, spaces don't literally match spaces in your input. Any whitespace in a format string causes *scanf to ignore whitespace before reading the next conversion.)

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If it were an float or double would the space still be necessary? I tried with that problem. I new it was the fscanf function causing trouble, once the while loop was eliminated but i googled and found nothing to support that space before %c. It works. Guess some things come with experience.

Quote:

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Originally Posted by fread

If it were an float or double would the space still be necessary? I tried with that problem. I new it was the fscanf function causing trouble, once the while loop was eliminated but i googled and found nothing to support that space before %c. It works. Guess some things come with experience.

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You need to get way better with googling, then. I'm not aware of any source that doesn't say something like

Quote:

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Originally Posted by man scanf

Code:

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    c    Matches a sequence of width count characters (default 1); the next
          pointer must be a pointer to char, and there must be enough room
          for all the characters (no terminating NUL is added).  The usual
          skip of leading white space is suppressed.  To skip white space
          first, use an explicit space in the format.

---

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or

Quote:

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Originally Posted by also man scanf

White space (such as blanks, tabs, or newlines) in the format string match any amount of white space, including none, in the input. Everything else matches only itself.

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But %f and %d skip white space by default (as you can see in the discussion of %c above, it is unusual in that respect).

do not use feof to control loop - read FAQ
use return value of fscanf for this purpose