This sample external C function acquires the fraction part from a real number.

• Body of the C function (file name: sample1.c)
  

  /* ALL RIGHTS RESERVED,COPYRIGHT (C)2007,HITACHI,LTD. */ /* LICENSED MATERIAL OF HITACHI,LTD. */ /************************************************************************/ /* name = HiRDB 08-03 sample program of C stored function 1 */ /************************************************************************/ #include <math.h> #include <stdio.h> /*---------------------------------------------------------------------*/ /* Define structure for receiving VARCHAR-type data */ /*---------------------------------------------------------------------*/ typedef struct varchar{ short len; char str[80]; }VCH; /************************************************************************/ /* name = sample1 */ /************************************************************************/ void func_modf(double *value, double *ret, short *ind1, short *ind_ret, char *sqlstate, VCH *routine_name, VCH *specific_name, VCH *message_text ) { double int_value; /* Set fraction part obtained by calling modf function as return value */ *ret = modf(*value, &int_value); /* Set indicator part of return value (non-null value) */ *ind_ret = 0; /* Set SQLSTATE (normal termination) */ memcpy(sqlstate, "00000", 5); /* Set null character string in message text */ message_text->len = sprintf(message_text->str, ""); }

The following is an example of defining and executing a C stored procedure using the C function shown above:

• Compiling the C file
  This example is for an HP-UX (32-bit mode). For examples for other OSs, see 10.2.1(4) Examples of C library file creation for different OSs.
  

  cc +z -c sample1.c

• Creating the C library file
  This example is for an HP-UX (32-bit mode). For examples for other OSs, see 10.2.1(4) Examples of C library file creation for different OSs.
  

  ld -b -o sample1.sl sample1.o

• Registering the C library file (using the INSTALL CLIB SQL statement)
  

  INSTALL CLIB 'sample1.sl' ;

• Defining the C stored function
  

  CREATE function func_modf( parm1 FLOAT ) RETURNS FLOAT LANGUAGE C EXTERNAL NAME 'sample1.sl!func_modf' PARAMETER STYLE RDSQL;

• Executing the C stored function
  

  select func_modf(double_value) from t1