How to tell if an array is empty in a structure?

[lurikeen]

I've got the following structure:

struct word
	{
	char theWord[30];
	int count;
	};
struct word arr[15000];

However, I can't get this for loop to work properly:

for (i=0;strcmp(arr[i].theWord,NULL)!=0 && dupeFlag!=1;i++)
		{
		printf("hi %s is the word, %s is temp\n",arr[i].theWord,temp);
		if (strcmp(arr[i].theWord,temp)==0)
			dupeFlag=1;
		}
//I've also tried, in place of "strcmp(arr[i].theWord,NULL)!=0": arr[i].theWord[0]!='\0', and so on.
//I don't want to initialize all 15000 arr[x].theWord's to NULL, so is there a way I can detect if they are garbage values or not? This currently gives me a segmentation fault.

By the way, I'm not allowed to use C++. Can't post the whole code since we get an F if our codes look similar... makes sense but its a bit annoying.

[MK27]

==0 and =='\0' almost certainly mean the same thing. But you should test the pointer for NULL.

There is no need to set all of them to NULL, just the one after the last one written into. Or else you keep a count of the number of strings written.

[cas]

You cannot tell whether a value is uninitialized or not, no. If you want to check to see whether the strings are empty (that is, have a length of zero), you have to make them empty. You could also create a flag in the struct that signals whether it contains a valid string... but then you'd have to initialize all those flags. So either way, you're going to have to do some sort of initialization that you don't appear to want to. Thankfully, it's very easy to initialize all the values to zero:

struct word arr[15000] = { 0 };

Now each string is empty (and each "count" member is set to zero).

As for using strcmp(), you should never pass it NULL; it expects strings, and NULL is not a string. That'd likely be the cause of your segfault. In your case, for strcmp(), you'd compare against ""; but as you noted, comparing the first character against '\0' means the same thing.

[MK27]

To test a string for NULL:

if (!(arr[i].theWord))

likewise, "if (arr[i].theWord)" tests not-NULL (which includes "\0\0\0\0\0", so if you use the method recommended by cas above, test "if (arr[i].theWord[0]=='\0')").

[lurikeen]

Thanks guys. Sorry for the late response, thats what I need to know