Thread: error checking file

i think
scanf("%s", &h) is not correct. if you want to store a string (as it seems) you should not use the & operator. And in that case you should declare h as char * h for example.
maybe...

Also, the fscanf is wrong for the same reason and thus probably also the function's user argument.

Second, this:

Code:

if (h != "user") ...

...isn't going to work. You need to use strcmp otherwise this bit of code is simply going to try and compare the address' of these two variables which are never going to be equal to each other.

And why use "a+" instead of something like "r" when opening the file?

Originally Posted by nacho4d

i think
scanf("%s", &h) is not correct. if you want to store a string (as it seems) you should not use the & operator. And in that case you should declare h as char * h for example.
maybe...

No. That will cause even more problems. You need to allocate memory first. So use a string array. And it's probably better to use fgets to read a string from input.
Nexus-ZERO, I recommend you read these resources:
http://cboard.cprogramming.com/showp...37&postcount=9
http://cpwiki.sf.net/User:Elysia/Indentation

Ok ive change my based on the suggestions i got. I just need to know how to set it so that it only accepts the user names in my txt file. (change the indentation once i get it working!)

Code:

int Login(int* user)
{
  char s[80];
  
  FILE * db;

  db = fopen ("text.txt","r");
  
	printf("Please enter your login: ");
	gets(s);
	
	if(strcmp(s, "pass")) {
	 printf("\n\nInvalid Login!\n\n");
	 return 0;
	 
	}
	
	return 1;
	
	fclose (db);
}

The function called "gets" is a very bad function - there is no protection if the user types more than 80 characters, and your application will most likely crash if this happens - try hanging on the "a" key for a bit and see what happens.

Code:

fgets(s, sizeof(s), stdin)

is a much more safe function. Just remember to throw this little bit of code after it:

Code:

if (s[strlen(s)-1] == '\n') s[strlen(s)-1] = 0;

--
Mats

Let me guess - you have done something else first, that involves scanf()?

--
Mats

I can't explain why it's working different from gets(), but you are getting a "newline" (enter key) in the input buffer from scanf(), so you need to read that out of the input buffer before calling fgets().

A simple "getchar()" after the last of your scanf() [last one before calling "Login" that is] should do the trick.

--
Mats

Assuming your file looks like

user
pass
user
pass

Then you could just read line-by-line (skipping the password line) and comparing the entered user with the one from the file. If you can match one of them, then it's valid, but if not, it's invalid.