[Mystique]

When you use GetPlayerFacingAngle you need to do this:

Code:

new Float:angle;
GetPlayerFacingAngle(playerid, angle);

Now angle is the facing angle you have when executing the command.
Now to show a function of using it:

Code:

if(strcmp(cmdtext, "/angle", true), ==0)
{
new Float:angle;
GetPlayerFacingAngle(playerid, angle);
new string[128];
format(string, sizeof(string), "Your facing angle is %d now.", angle);
SendClientMessage(playerid,0xFFFFFFAA,string);
return 1;
}

That's just basically how it works.

Edit: Your post wasn't there when I started writing this r0b, that's why I wrote the same but a little more also.