Ensure that there exists a pointer to the character array that has been passed as an actual argument to the C routine. Also generate a variable that contains the length of the actual character argument and call it ‘arg_length’.

GENPTR_CHARACTER_ARRAY(arg)

arg

GENPTR_CHARACTER_ARRAY(x)

will expand as follows:

All Unix:
VAX/VMS:	char $\ast$x = x_arg-$>$dsc$a_pointer;
	int x_length = x_arg-$>$dsc$w_length;

On Unix systems, this macro is null, but on a VAX/VMS system, this macro actually declares the variables that are the pointer to the character string and the integer that contains its length.