Regarding warning, you are missing a few function prototypes. Mention all the funtions used in your program before the ‘main()’ funtion. i.e. ” void display_lcd(unsigned char *str);”
Regarding error, this is a code which I usually use,
void display_lcd(unsigned char *str)
{
while(*str!=0)
{
data_lcd(*str);
str++;
}
}
Hope this helps, good Luck.