Difference between revisions of "Dbxrewind()"
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| Line 12: | Line 12: | ||
<input parameters> | <input parameters> | ||
| − | char *dbx; /* Tagged index file descriptor */ | + | char *dbx; /* Tagged index file descriptor */ |
<output parameters> | <output parameters> | ||
| Line 21: | Line 21: | ||
==RETURN VALUE== | ==RETURN VALUE== | ||
| − | The dbxrewind() 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. | + | The dbxrewind() function returns 0 for success, or < 0 if an error occurs. See the section on [[Library Return Code Values|return code values]] for a detailed list of return codes. |
| + | |||
==DESCRIPTION== | ==DESCRIPTION== | ||
The dbxrewind() function positions the access pointer at the beginning of the active tag in the specified tagged index file, .DBX. | The dbxrewind() function positions the access pointer at the beginning of the active tag in the specified tagged index file, .DBX. | ||
| − | |||
| Line 37: | Line 37: | ||
<code lang="c"> | <code lang="c"> | ||
#include <stdio.h> | #include <stdio.h> | ||
| − | #include "dbl.h" | + | #include "dbl.h" /* Recital/Library include file */ |
| − | #include "dblproto.h" /* Recital/Library prototype file */ | + | #include "dblproto.h" /* Recital/Library prototype file */ |
static dBFIELD fields[6] = { | static dBFIELD fields[6] = { | ||
| Line 56: | Line 56: | ||
main() | main() | ||
{ | { | ||
| − | + | int rc; /* Return Code for error handling */ | |
| − | + | char *dbf; /* File descriptor for table */ | |
| − | + | char *dbx; /* File descriptor for tagged index */ | |
| − | + | int i; /* Loop control variable */ | |
| − | + | char record[58]; /* Array of char for records */ | |
| − | + | char nextkey[10][20]; /* Key buffers */ | |
| − | + | char status; /* Deleted record flag */ | |
| − | + | long rec_no[10]; /* Record number array */ | |
| − | + | rc = dbdcache(100); | |
| − | + | errorproc("dbdcache()","table cache specified.", rc); | |
| − | + | rc = dbicache(100); | |
| − | + | errorproc("dbicache()", "index cache specified.", rc); | |
| − | + | rc = dbfilemode(1,0); | |
| − | + | rc = dbopen("shipwreck.dbf", &dbf); | |
| − | + | errorproc("dbopen()","table opened in shared mode.", rc); | |
| − | + | rc = dbxopen(dbf, "shipwreck.dbx", &dbx); | |
| − | + | errorproc("dbxopen()","tagged index opened.", rc); | |
| − | + | rc = dbxfwd(dbx); | |
| − | + | errorproc("dbxfwd()", "index pointer placed at bottom.", rc); | |
| − | + | rc = dbxpkey(dbx, nextkey[0], rec_no); | |
| − | + | errorproc("dbxpkey()", "previous key found in tagged index.", rc); | |
| − | + | printf("\t\tprev key: \t%s\n", nextkey[0]); | |
| − | + | rc = dbxgetpr(dbf, dbx, record, &status); | |
| − | + | errorproc("dbxgetpr()", "previous record (by key) retrieved.", rc); | |
| − | + | printf("Previous: \t%s\n", record); | |
| − | + | rc = dbxrewind(dbx); | |
| − | + | errorproc("dbxrewind()", "Tagged index rewound.", rc); | |
| − | + | for( i = 1; i <= 6; i++) { | |
| − | + | rc = dbxgetnr(dbf, dbx, record, &status); | |
| − | + | printf("\t\t%d: %s\n", i,record); | |
| − | + | } | |
| − | + | errorproc("dbxgetnr()", "6 records retrieved by tag key.", rc); | |
| − | + | rc = dbxnkey(dbx, nextkey[0], rec_no); | |
| − | + | errorproc("dbxnkey()", "next key retrieved in tagged index.", rc); | |
| − | + | printf("\t\tnext key: \t%s\n", nextkey[0]); | |
| − | + | 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) | static void errorproc(func, str, rc) | ||
| Line 111: | Line 111: | ||
char *str; | char *str; | ||
int rc; | int rc; | ||
| − | { | + | { |
| − | + | if ( rc != SUCCESS ) { | |
| − | + | printf("\n Error performing function %s -> %d\n", func, rc); | |
| − | + | exit(1); | |
} | } | ||
| − | printf("Function: t%s, t%s - | + | printf("Function: \t%s, \t%s - Ok\n", func, str); |
return; | return; | ||
} | } | ||
Latest revision as of 10:27, 6 May 2009
PURPOSE
position access pointer to beginning of tag
SYNOPSIS
#include "dbl.h" int dbxrewind(dbx) <input parameters> char *dbx; /* Tagged index file descriptor */ <output parameters> none
RETURN VALUE
The dbxrewind() 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
The dbxrewind() function positions the access pointer at the beginning of the active tag in the specified tagged index file, .DBX.
EXAMPLE
The following example opens the table and tag index, goes to the bottom of the index, reads the previous key by position then by key, rewinds the index, reads the next 6 records in the index, reads the next record by key and then closes the files.
#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 */ int i; /* Loop control variable */ char record[58]; /* Array of char for records */ char nextkey[10][20]; /* Key buffers */ char status; /* Deleted record flag */ long rec_no[10]; /* Record number array */ rc = dbdcache(100); errorproc("dbdcache()","table cache specified.", rc); rc = dbicache(100); errorproc("dbicache()", "index cache specified.", rc); rc = dbfilemode(1,0); rc = dbopen("shipwreck.dbf", &dbf); errorproc("dbopen()","table opened in shared mode.", rc); rc = dbxopen(dbf, "shipwreck.dbx", &dbx); errorproc("dbxopen()","tagged index opened.", rc); rc = dbxfwd(dbx); errorproc("dbxfwd()", "index pointer placed at bottom.", rc); rc = dbxpkey(dbx, nextkey[0], rec_no); errorproc("dbxpkey()", "previous key found in tagged index.", rc); printf("\t\tprev key: \t%s\n", nextkey[0]); rc = dbxgetpr(dbf, dbx, record, &status); errorproc("dbxgetpr()", "previous record (by key) retrieved.", rc); printf("Previous: \t%s\n", record); rc = dbxrewind(dbx); errorproc("dbxrewind()", "Tagged index rewound.", rc); for( i = 1; i <= 6; i++) { rc = dbxgetnr(dbf, dbx, record, &status); printf("\t\t%d: %s\n", i,record); } errorproc("dbxgetnr()", "6 records retrieved by tag key.", rc); rc = dbxnkey(dbx, nextkey[0], rec_no); errorproc("dbxnkey()", "next key retrieved in tagged index.", rc); printf("\t\tnext key: \t%s\n", nextkey[0]); 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; }
