XppParamList pList
Pointer to the Xbase++ parameter list, which is used to provide access to the parameter.
Function _partype() Foundation
Determines the type of a parameter or the number of parameters.
Syntax
ULONG _partype(XppParamList pList, ULONG ulIndex);Parameters
ULONG ulIndex
Position of the parameter whose type is to be determined (first parameter is one) or zero when the number of parameters is to be returned.
Return
When ulIndex is equal to NULL the number of parameters passed to the actual function is returned. If ulIndex is not equal to NULL, _parType() returns the type of the parameter and whether the parameter was passed by reference.
Description
_partype() is used to determine the type of a parameter before its value is accessed. (In CA-Clipper the function _parinfo() was used to do this).
It should be noted that for some types more then one bit is masked in the return value. Furthermore, the numeric value representing a type may change in future Xbase++ versions. Because of these reasons the return value should be tested with one of the macros defined in the header file xpppar.h. The following table lists the macros and the types for which the macro evaluates to true:
Type checking macros
| Macro | Type | Meaning |
|---|---|---|
| XPP_IS_UNDEF() | XPP_UNDEF | NIL |
| XPP_IS_CHAR() | XPP_CHARACTER or | Character string |
| XPP_MEMO | ||
| XPP_IS_MEMO() | XPP_MEMO | Memo character string |
| XPP_IS_NUM() | XPP_NUMERIC or | Numeric |
| XPP_DOUBLE | ||
| XPP_IS_FLOAT() | XPP_DOUBLE | Floating point |
| XPP_IS_LOGIC() | XPP_LOGICAL | Logical |
| XPP_IS_DATE() | XPP_DATE | Date |
| XPP_IS_ARRAY() | XPP_ARRAY | Array |
| XPP_IS_BLOCK() | XPP_BLOCK | Code block |
| XPP_IS_OBJECT() | XPP_OBJECT | Object |
| XPP_IS_REFPAR() | Parameter was passed | |
| by reference |
Examples
/*
Test whether a parameter was passed by reference and change its
value.
*/
#include <xpppar.h>
if ( XPP_IS_REFPAR( _partype(<pList>, 6) ) )
{
_storc("This string is returned to Xbase++.",
<pList>, 6);
}
/*
get the number of parameters
*/
#define PCOUNT(paramList) _partype(paramList, 0)
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