How to check if C string is empty

Since C-style strings are always terminated with the null character (\0), you can check whether the string is empty by writing

do {
   ...
} while (url[0] != '\0');

Alternatively, you could use the strcmp function, which is overkill but might be easier to read:

do {
   ...
} while (strcmp(url, ""));

Note that strcmp returns a nonzero value if the strings are different and 0 if they're the same, so this loop continues to loop until the string is nonempty.

Hope this helps!

If you want to check if a string is empty:

if (str[0] == '\0')
{
    // your code here
}

If the first character happens to be '\0', then you have an empty string.

This is what you should do:

do {
    /* 
    *   Resetting first character before getting input.
    */
    url[0] = '\0';

    // code
} while (url[0] != '\0');