Dbxopen()

PURPOSE

open a .dbx index file

SYNOPSIS

#include "dbl.h"
 
	int	dbxopen(dbf, filename, dbx);
 
	<input parameters>
	char	*dbf;			/* .DBF file descriptor */
	char	*filename;		/* Address of a buffer containing the name of a .DBX file to be opened */
 
	<output parameters>
	char	*dbx;		/* The .DBX file descriptor */

RETURN VALUE

The dbxopen() function returns 0 for success , or < 0 if an error occurs. See the section on return code values for a detailed list of return codes.

DESCRIPTION

This function opens a .DBX file and returns its file descriptor. A call to The dbxclose() function releases the file descriptor.

EXAMPLE

The following example opens the index for the shipwreck.dbf table, checks the number of tags, then returns detailed information about the tags

#include <stdio.h>
#include "dbl.h"			/* Recital/Library include file */
#include "dblproto.h"		/* Recital/Library prototype file */
 
	static	dBFIELD fields[6] = {
		"VESSEL",	'C',	18,	0,	0,
		"LAT",	'N',	4,	1,	0,
		"LONG",	'N',	4,	1,	0,
		"AMOUNT",	'N',	10,	0,	0,
		"DATE",	'D',	8,	0,	0,
		"FLAG",	'C',	9,	0,	0
	};
 
	static void errorproc(
		char	*func,
		char	*str,
		int	rc);
 
	main()
	{
		int	rc; 				/* Return Code for error handling */
		char	*dbf; 			/* File descriptor for table */
		char	*dbx; 			/* File descriptor for tagged index */
		char	keytype; 			/* Variable for varying keytype */
		char	tagname[21]; 		/* Storage location for tag name */
		char	keyexpr[512]; 		/* Storage location for key expr */
		char	forexpr[512]; 		/* Storage location for for expr */
		int	kexprlen; 			/* The key expression length */
		int	keylen; 			/* The key length */
		int	i; 				/* Loop control variable */
		int	keyunique;			/* Boolean for unqiue tag key */
		int	keydescend;		/* Boolean for descending tag key */
		int	notags;			/* Number of tags in a dbx file */
 
		rc = dbdcache(100);
		errorproc("dbdcache()","table cache specified.", rc);
		rc = dbicache(100);
		errorproc("dbicache()", "index cache specified.",rc);
		rc = dbfilemode(0,0);
		rc = dbopen("shipwreck.dbf", &dbf);
		errorproc("dbopen()","table opened in exclusive mode.", rc);
		rc = dbxopen(dbf, "shipwreck.dbx", &dbx);
		errorproc("dbxopen()","tagged index opened.", rc);	
		rc = dbxnotags(dbx, &notags);
		errorproc("dbxnotags()","tagged index count obtained.", rc);
		printf("\t	  Key count: \t%d\n", notags );
 
		for (i = 1; i <= notags; i++) {
			rc = dbxkexpr(dbx, 
			  &i,
			  tagname,
			  &keytype, 
			  keyexpr, 
			  forexpr,
			  &kexprlen, 
			  &keylen,
			  &keyunique,
			  &keydescend);
			errorproc("dbxkexpr()", "key information retrieved.", rc);
			printf("\t	  Key number: \t%d\n", i );
			printf("\t	  Key name: \t%s\n", tagname );
			printf("\t	  Key type: \t%c\n", keytype );
			printf("\t	  Key expression: %s\n", keyexpr);
			printf("\t	  Key length: %d   Expression length: %d\n", kexprlen, keylen);
			printf("\t	  For expression: %s\n", forexpr);
			printf("\t	  Key unique: \t%s\n", keyunique ? "Yes" : "No" );
			printf("\t	  Key descending: \t%s\n", keydescend?"Yes":"No" );
		}	
 
		rc = dbxclose(dbx);
		errorproc("dbxclose()", "tagged index closed.", rc);
		rc = dbclose(dbf);
		errorproc("dbclose()", "table closed.", rc);
		exit(0);
	}
 
	static void errorproc(func, str, rc)
	char	*func;
	char	*str;
	int	rc;
	{
		if ( rc != SUCCESS ) {
			printf("\n  Error performing function %s -> %d\n", func, rc);
			exit(1);
	}
	printf("Function: \t%s, \t%s - Ok\n", func, str);
	return;
}

SEE ALSO

dbxclose(), dbxcreate(), dbxkexpr()