How to Call a C program in PL/SQL?

For the DB installed in Linux platform
Compiled the C code and generated .so file
gcc -o calc_tax.so -shared calc_tax.c

Step1: Conn scott/tiger@orcl

Step2: CREATE OR REPLACE LIBRARY c_lib
AS
'/tmp/calc_tax.so';

Note : You should have CREATE LIBRARY privelege

Step3: CREATE OR REPLACE FUNCTION tax_amt(x BINARY_INTEGER)
RETURN BINARY_INTEGER
AS LANGUAGE C
LIBRARY c_lib
NAME "calc_tax";

calc_tax.c is given below
-----------------------------------------------------
calc_tax(n)

int n;

{

int tax;

tax = (n*8)/100;

return(tax);

}



main()

{

int tot_ord;

printf("Enter the Order Total ");

scanf("%d",&tot_ord);

printf("\n%d", calc_tax(tot_ord));

printf("\n\n");

}



Step4: SELECT tax_amt(10000)
FROM DUAL;