Dynamic memory allocation Post: 302231527

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Top Forums Programming Dynamic memory allocation Post 302231527 by ramen_noodle on Tuesday 2nd of September 2008 02:11:21 PM

09-02-2008

Registered User

This is one of those problems that I've always enjoyed because most of the text processing utilities we use have statically defined or user defined limits in moving parts. (Think gawk, perl, etc...).
The Heathfield link is as good an interface as I've seen.
A quick (and easily broken) data structure and some logic for working with the idea.

Code:


typedef struct _line {
int len;
long lineno;
char *record;
struct _line *prv;
} LINE;

LINE *newallocline(int l, long rno, char *data, LINE *prv) {
LINE *new = NULL;

                    if ( (new = malloc(sizeof(new))) == NULL) {return NULL;}
                    new->record = malloc(l * sizeof(char));
                    if (new->record == NULL) {free(new); new = NULL; return NULL;}
                    strncpy(new->record,data,l);
                    new->lineno = rno;
                    new->prv = prv;
                    return new;
}                    
                                      
/*pseudo code
*prv = NULL;
* while (gets input into absurdly static large_buffer (500000 characters) for line)
        if ( (cnew = newallocline(strlen(large_buffer),cnt++,large_buffer,prv)) == NULL) {error();}
        prv = cnew;
}
*/

ramen_noodle

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px_retrieve_record

PX_RETRIEVE_RECORD(3)					     Library Functions Manual					     PX_RETRIEVE_RECORD(3)

NAME

       PX_retrieve_record -- Returns record in Paradox file

SYNOPSIS

       #include <paradox.h>

       pxval_t ** PX_retrieve_record(pxdoc_t *pxdoc, int recno)

DESCRIPTION

       Returns the record with the given number in a Paradox file. The first record has number 0, the last one has number_of_records-1.

       If you are accessing several records, do it in ascending order, because this is the most efficient way.

       The return value is an array of field values. Each value is stored in a structure like the following:

       typedef struct px_val pxval_t;
       struct px_val {
       char isnull;
       int type;
       union {
       long lval;
       double dval;
       struct {
       char *val;
       int len;
       } str;
       } value;
       };

       The  element  isnull  is  set  to  1 if the value is NULL otherwise it is set to 0. type 	       is the type of the paradox field as
       defined in paradox.h.  A field value can be either a long int, a double or a string, depending on the paradox field type. The paradox field
       types  pxfShort,  pxfLong,  pxfDate,  pxfTime,  pxfLogical,  and  pxfAutoInc are returned as long int values.  pxfTimestamp, pxfNumber, and
       pxfCurrency are returned as double values and all remaining paradox field types are stored as strings with the length in value.len. You can
       rely on strings being Null terminated. Blobs are stored as string but are not guarented to be Null terminated.

       The  paradox  field  types  pxfTimestamp,  pxfTime,  an	pxfDate  use an uncommon format which can be converted into a string with PX_time-
       stamp2string(3), PX_time2string(3), and PX_date2string(3).

RETURN VALUE

       Returns a pointer on success and NULL on failure.

SEE ALSO

       PX_update_record(3), PX_timestamp2string(3), PX_time2string(3), PX_date2string(3)

AUTHOR

       This manual page was written by Uwe Steinmann uwe@steinmann.cx.

															     PX_RETRIEVE_RECORD(3)