Difference between revisions of "Dbxkexpr()"
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<input parameters> | <input parameters> | ||
| − | char *dbx; | + | char *dbx; /* Tagged index file descriptor */ |
<input/output parameters> | <input/output parameters> | ||
| − | int tagno; | + | int tagno; /* If tagno > 0, then it is used as input as the tag number, otherwise |
| − | char *tagname; /* If tagno <= 0, then it is used as input as the tagname, otherwise the tagname corresponding to the specific tagno is returned. | + | the tag number corresponding to the specified tagname is returned. */ |
| + | char *tagname; /* If tagno <= 0, then it is used as input as the tagname, otherwise | ||
| + | the tagname corresponding to the specific tagno is returned. */ | ||
<output parameters> | <output parameters> | ||
| − | char keytype; /* Tag key data type: | + | char keytype; /* Tag key data type: |
| − | + | 'C' - Character | |
| − | + | 'N' - Numeric | |
| − | + | 'D' – Date */ | |
| − | char | + | char *keyexpr; /* Tag key expression */ |
| − | char | + | char *forexpr; /* Tag for expression */ |
| − | int *keyexprlen; /* Length of the tag key expression | + | int *keyexprlen; /* Length of the tag key expression */ |
| − | int *keylen; /* Tag key length | + | int *keylen; /* Tag key length */ |
| − | int *keyunique; | + | int *keyunique; /* 1 if tag is unique, 0 otherwise */ |
| − | int *keydescend; /* 1 if tag is in descending order, 0 otherwise */ | + | int *keydescend; /* 1 if tag is in descending order, 0 otherwise */ |
</code> | </code> | ||
Revision as of 13:48, 1 April 2009
PURPOSE
get the key expression for a specified tag
SYNOPSIS
#include "dbl.h" int dbxkexpr(dbx, tagno, tagname, keytype, keyexpr, forexpr, keyexprlen, keylen, keyunique, keydescend); <input parameters> char *dbx; /* Tagged index file descriptor */ <input/output parameters> int tagno; /* If tagno > 0, then it is used as input as the tag number, otherwise the tag number corresponding to the specified tagname is returned. */ char *tagname; /* If tagno <= 0, then it is used as input as the tagname, otherwise the tagname corresponding to the specific tagno is returned. */ <output parameters> char keytype; /* Tag key data type: 'C' - Character 'N' - Numeric 'D' – Date */ char *keyexpr; /* Tag key expression */ char *forexpr; /* Tag for expression */ int *keyexprlen; /* Length of the tag key expression */ int *keylen; /* Tag key length */ int *keyunique; /* 1 if tag is unique, 0 otherwise */ int *keydescend; /* 1 if tag is in descending order, 0 otherwise */
RETURN VALUE
The dbxkexpr() 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 dbxkexpr() function obtains the index tag information from the specified tagged index file, .DBX for a tag number or name.
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, ¬ags); errorproc("dbxnotags()","tagged index count obtained.", rc); printf("t Key count: t%dn", 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%dn", i ); printf("t Key name: t%sn", tagname ); printf("t Key type: t%cn", keytype ); printf("t Key expression: %sn", keyexpr); printf("t Key length: %d Expression length: %dn", kexprlen, keylen); printf("t For expression: %sn", forexpr); printf("t Key unique: t%sn", keyunique ? "Yes" : "No" ); printf("t Key descending: t%sn", 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 -> %dn", func, rc); exit(1); } printf("Function: t%s, t%s - Okn", func, str); return; }
