Man page - gd_get_string(3)

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Manual

gd_get_string

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
HISTORY
SEE ALSO

NAME

gd_get_string — retrieve STRING or SARRAY data from a Dirfile database

SYNOPSIS

#include <getdata.h>

size_t gd_get_string(DIRFILE * dirfile , const char * field_code , size_t len , char * data_out );

DESCRIPTION

The gd_get_string () function queries a dirfile(5) database specified by dirfile for the string scalar field_code , which should not contain a representation suffix. The first len characters of the string scalar are stored in the user-supplied buffer data_out . If field_code refers to a SARRAY field, the first element is returned.

The dirfile argument must point to a valid DIRFILE object previously created by a call to gd_open (3).

If len equals zero, or if data_out equals NULL, no data will be copied to data_out , but the length of the string scalar will still be returned by gd_get_string (). Otherwise, the argument data_out must point to a valid memory location of sufficient size to hold at least len characters. If the length of the string scalar is greater than len , data_out will not be NUL-terminated.

The gd_get_sarray (3) function provides another way of retrieving STRING data, but without having to know the length of the returned string in advance. The code:

size_t len = gd_get_string( dirfile , field_code , 0, NULL);
char * string = malloc( len );
gd_get_string( dirfile , field_code , len , string );

which ensures the whole string, including the terminating NUL, is returned, can be replaced with, simply:

const char * string;
gd_get_sarray( dirfile , field_code , & string );

with the added benefit of not having manage the memory for the string.

RETURN VALUE

On success, gd_get_string () returns the actual length of the specified string scalar, including space for the trailing NUL-character. A return value greater than len indicates that the output string is not NUL-terminated.

On error, this function returns 0 and stores a negative-valued error code in the DIRFILE object which may be retrieved by a subsequent call to gd_error (3). Possible error codes are:
GD_E_BAD_CODE

The field specified by field_code was not found in the database.

GD_E_BAD_DIRFILE

An invalid dirfile was supplied.

GD_E_BAD_FIELD_TYPE

The supplied field_code referred to a field of type other than STRING or SARRAY .

GD_E_INTERNAL_ERROR

An internal error occurred in the library while trying to perform the task. This indicates a bug in the library. Please report the incident to the maintainer.

A descriptive error string for the error may be obtained by calling gd_error_string (3).

HISTORY

The get_string () function appeared in GetData-0.4.0.

In GetData-0.7.0, this function was renamed to gd_get_string ().