5.2.27hdfql_subcursor_absolute

#Syntax

#Description

Move the subcursor in use to an absolute position position within the result subset. The first element of the result subset is at position zero, while the last element is located at the position returned by hdfql_subcursor_get_count - 1. An attempt to move the subcursor before the first element will return an error and set the position of the subcursor to minus one, while an attempt to move the subcursor after the last element will return an error and set the position of the subcursor to the number of elements in the result subset.

#Parameter(s)

cursor – pointer to a cursor to move the subcursor in use to an absolute position within the result subset. If the pointer is NULL (in C), the subcursor of the cursor in use is moved to an absolute position instead. The equivalent of a NULL pointer in C++, Java, Python, C#, Fortran, R, and MATLAB HDFql wrappers is NULL, null, None, null, NULL(), NULL, and NaN, respectively. While in C cursor is mandatory, in C++, Java, Python, C#, Fortran, R, and MATLAB it is optional (when not specified, the subcursor of the cursor in use is moved to an absolute position instead).

position – long long that specifies the absolute position to which to move the subcursor. If positive, the subcursor will position itself with reference to the beginning of the result subset. If negative, the subcursor will position itself with reference to the end of the result subset.

#Return

int – depending on the success in moving the subcursor to an absolute position within the result subset, it can be HDFQL_SUCCESS, HDFQL_ERROR_EMPTY, HDFQL_ERROR_BEFORE_FIRST, or HDFQL_ERROR_AFTER_LAST.

#Example(s)

// create an HDF5 dataset named "my_dataset" of data type variable-length int of two dimensions (size 2x2)
hdfql_execute("CREATE DATASET my_dataset AS VARINT(2, 2)");

// insert (i.e. write) values into dataset "my_dataset" 
hdfql_execute("INSERT INTO my_dataset VALUES(((7, 8, 5), (9)), ((6, 1, 2, 3), (4, 0)))"); 

// select (i.e. read) data from dataset "my_dataset" and populate cursor in use with it 
hdfql_execute("SELECT FROM my_dataset");

// move the cursor in use to the first position within the result set 
hdfql_cursor_first(NULL);

// move the subcursor in use to absolute position 2 within the result subset 
hdfql_subcursor_absolute(NULL, 2);

// display current element of the subcursor in use within the result subset (should be "Current element of subcursor is 5")
printf("Current element of subcursor is %d", hdfql_subcursor_get_int(NULL));

// move the subcursor in use to absolute position -2 within the result subset 
hdfql_subcursor_absolute(NULL, -2); 

// display current element of the subcursor in use within the result subset (should be "Current element of subcursor is 8")
printf("Current element of subcursor is %d", hdfql_subcursor_get_int(NULL));