Question: Is it possible to edit the text within a cell in datatables. So that when the user double clicks on the cell it becomes editable ?

Thanks

Answer: 
No. I've seen all three. Personally, I use 

```
if (!str[0])

```

Using strlen is a waste of processor time and not safe unless you can guarantee the string is terminated.
I would definitely go with `strlen(str) == 0`, just for clarity.

The function should be implemented something like this:

```
int strlen(char *s) {
  int len = 0;
  while(*(s++)) len++;
  return len;
}

```

so there will be no big overhead.

**Edit:** assuming you are sure that the string is actually zero terminated.