Warning comparison between pointer and integer

In this line ...

if (*message == "\0") {

... as you can see in the warning ...

warning: comparison between pointer and integer
      ('int' and 'char *')

... you are actually comparing an int with a char *, or more specifically, an int with an address to a char.

To fix this, use one of the following:

if(*message == '\0') ...
if(message[0] == '\0') ...
if(!*message) ...

On a side note, if you'd like to compare strings you should use strcmp or strncmp, found in string.h.

This: "\0" is a string, not a character. A character uses single quotes, like '\0'.

It should be

if (*message == '\0')

In C, simple quotes delimit a single character whereas double quotes are for strings.