IBM Visualization Data Explorer Programmer's Reference

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DXComponentReq, DXComponentOpt, DXComponentReqLoc, DXComponentOptLoc

Function

Access or typecheck a component in a Field.

Syntax

#include <dx/dx.h>

Error DXComponentReq(Array a, Pointer *data, int *n, int nreq, Type t, int dim)
Error DXComponentOpt(Array a, Pointer *data, int *n, int nreq, Type t, int dim)
Error DXComponentReqLoc(Array a, Pointer *data, int *n, int nreq, Type t, int dim)
Error DXComponentOptLoc(Array a, Pointer *data, int *n, int nreq, Type t, int dim)

Functional Details

Note:These routines will become obsolete in a future version of Data Explorer. In their place, it is recommended that you now use DXGetComponentValue and DXGetArrayInfo.

The four routines have identical calling sequences, but differ as follows.

First, DXComponentOpt and DXComponentReq return pointers to the global copy of the Array data, while DXComponentOptLoc and DXComponentReqLoc return pointers to a local copy of the Array data, and should be matched by a DXFreeArrayDataLocal call.

Second, DXComponentReq and DXComponentReqLoc consider it an error if the component is missing (a is NULL), while DXComponentOpt and DXComponentOptLoc consider the component optional and do not consider a NULL a to be an error.

If data is not NULL, a pointer to a global or local copy of the data is returned in *data. If n is not NULL, the number of items in the Array is returned in *n. If n is NULL, the number of Array items must be nreq. The type of the Array must be t. If dim is 0, the Array must have rank 0 (scalar). If dim is nonzero, the Array must have rank 1 and shape equal to dim.

The type is one of the following:


TYPE_BYTE            TYPE_HYPER        TYPE_SHORT
TYPE_UBYTE           TYPE_INT          TYPE_USHORT
TYPE_DOUBLE          TYPE_UINT         TYPE_STRING
TYPE_FLOAT

Note:These functions will expand compact data Arrays and use extra memory.

Return Value

Returns OK or returns ERROR and sets an error code.

See Also

DXGetArrayData, DXGetArrayInfo, DXGetComponentValue

12.1 , "Field Class".


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