Check the return status of scanf

This is my code I'm not sure where I've gone wrong or how I do it but I keep getting this message back... Any help would be great.


75. fscanf(fp, "%d", &check);
==> You have not checked the return status of scanf.

90. fscanf(fp, "%f", &hour);
==> You have not checked the return status of scanf.

Code:

---

      fscanf(fp, "%d", &check);
      if (feof(fp))
      {
        fclose(fp);
        break;
      }
      fscanf(fp, "%s", stay);
      if (feof(fp))
      {
        fclose(fp);
        break;
      }
      fscanf(fp, "%s", taken);
      if (feof(fp))
      {
        fclose(fp);
        break;
      }
      fscanf(fp, "%f", &hour);

---

Maybe it is because since you have closed your file you can't read from it.
For example if the first fscanf succeeds the other won't work.You must fix your code.

Why u r using these many of 'if's' for the same purpose in ur program??

Message just says what it says - you don't check the return value:

Code:

---

int count = fscanf(fp,"%d",&value);
if(count != 1)
{
  //Hey - we have problem with reading from the file
}

---

> fscanf(fp, "%d", &check);
Meaning it should be

if ( fscanf(fp, "%d", &check) == 1 )
// it was successful.

Quote:

---

Originally Posted by maven

Why u r using these many of 'if's' for the same purpose in ur program??

---

How would you recommend doing it?

Thanks for the help on the returning scanf I realise my mistake now.

Since || is short-cutting, you could do something like this:

Code:

---

if(fscanf(fp, "%d", &check) != 1 || fscanf(fp, "%s", stay) != 1
    || fscanf(fp, "%s", taken) != 1 || fscanf(fp, "%f", &hour) != 1) {

    /* failed */
}

---

Better yet:

Code:

---

if(fscanf(fp, "%d%s%s%f", &check, stay, taken, &hour) != 4) {
    /* failed */
}

---

I tried the second one originally but it gives me a tonne of syntax errors and the first example causes and error in the program (the program freezes) when it tests weather the file has a corrputed float.

thats cause you havent provided the rest of the code. The error is there probably

Im willing to bet you have something like this:

Code:

---

char *stay;
fscanf(fp, "%s", stay);

---

correct?

Fixed it... Thanks

Nice to see you've been listening :rolleyes:

Code:

---

char buff[BUFSIZ];
while ( fgets( buff, BUFSIZ, fp ) != NULL ) {
  if ( sscanf( buff, "%d %s %s %f", &check, stay, taken, &hour ) == 4 ) {
    // Now do your linked list bit
  } else {
    // some error?
  }
}

---

> newnode = (Node*)malloc(sizeof(Node));
Read the FAQ on casting malloc.