How to write a string in 32 protected mode in C language

I would like to print a string on screen in protected mode.I enclose the code.When I go to run it, GCC warns me that the function argument has a type that is incompatible with the parameter.Can anyone help me out?

void write_string( int colour, const char *string );void main(){   int colour = 4;   const char string[] = "Ciaoooooo";     write_string(colour, &string);  }void write_string( int colour, const char *string ){   volatile char *video = (volatile char*)0xB8000;   while( *string != 0 )   {       *video++ = *string++;       *video++ = colour;   }}```