UDF PROGRAMMERS MANUAL





 read_idf (1) 
     UDF PROGRAMMERS MANUAL
     read_idf (1)
 


 
  NAME   read_idf




 SYNOPSIS  




 #include "libbase_udf.h"


 ByTe_2
     read_idf
     (u_ByTe_4 Key, ByTe_1 *Ext,
                       u_ByTe_2 Ver, ByTe_1 *Var,
                       ByTe_2 Quan, ByTe_2 Num, 
                       ByTe_4 Start, ByTe_2 NumV);







 INPUT DEFINITIONS  








 Key
     -
     UDF data key


 Ext
     -
     UDF file extension


 Ver
     -
     Version number


 Var
     -
     Output variable holding the returned VIDF data


 Quan
     -
     The VIDF field to return


 Num
     -
     The VIDF table or constant number valid only if table
                      or constant data is being returned


 Start
     -
     If the field is an array field, this is the offset into
                      the array at which to begin acquisition


 NumV
     -
     If the field is an array field, this is the number of
                      elements to return.  -1 is used to return full array.  
     







  DESCRIPTION  
 read_idf() accesses data fields from the VIDF identified with 
Key and Ver and returns the data in the variable Var.  
The field being returned is specified in Quan using the identifiers 
listed in the last column of the 
VIDF description tables.  If retrieved field is an array quantity then 
the returned values can be any subset of the array.  Start indicates 
the beginning position in the array at which to return data and NumV 
is the number of values to return.  A NumV of -1 will cause all 
values up to an including the last value in the array to be returned.




If the quantity being returned is a field in either a TABLE or
CONSTANT block then Num specifies which TABLE or
CONSTANT the field is to be taken from.




It is the responsibility of the caller to ensure that Var is of
sufficient size to hold all of the returned data.




Under normal conditions Ext should be set to a NULL string.  
Setting Ext to a non-NULL string will cause the file_pos
routine to attempt to use the appropriate named UDF header and data
files but with the string .Ext appended to it.  The file must 
exist in the current working directory.  




  RETURN VALUE  
  On success, ALL_OKAY is returned, otherwise an error code is
returned.




  ERRORS  

 IDF_NOT_FOUND  No opened file (file_open not called?) 
 IDF_MANY_BYTES  Requested more elements from array than exists.
 IDF_NO_ENTRY  Requesed data not available
 IDF_TBL_NUM  Requested table number larger than tables available 
 IDF_CON_NUM  Requested constant number larger than constants available 
  




  APPLICABLE FORMATS  
  UDF V2.2, IDFS V2.1




  RESTRICTIONS  
 None.




  SEE ALSO  
ret_codes(1H)
idf_defs(1)










 UDF V2.2 
     July 31, 1999
     UDF V2.2
 










  

    
    TOC
    HOME