PdhMakeCounterPathA function (pdh.h)

Article
02/09/2023

Creates a full counter path using the members specified in the PDH_COUNTER_PATH_ELEMENTS structure.

Syntax

PDH_FUNCTION PdhMakeCounterPathA(
  [in]      PPDH_COUNTER_PATH_ELEMENTS_A pCounterPathElements,
  [out]     LPSTR                        szFullPathBuffer,
  [in, out] LPDWORD                      pcchBufferSize,
  [in]      DWORD                        dwFlags
);

Parameters

[in] pCounterPathElements

A PDH_COUNTER_PATH_ELEMENTS structure that contains the members used to make up the path. Only the szObjectName and szCounterName members are required, the others are optional.

If the instance name member is NULL, the path will not contain an instance reference and the szParentInstance and dwInstanceIndex members will be ignored.

[out] szFullPathBuffer

Caller-allocated buffer that receives a null-terminated counter path. The maximum length of a counter path is PDH_MAX_COUNTER_PATH. Set to NULL if pcchBufferSize is zero.

[in, out] pcchBufferSize

Size of the szFullPathBuffer buffer, in TCHARs. If zero on input, the function returns PDH_MORE_DATA and sets this parameter to the required buffer size. If the buffer is larger than the required size, the function sets this parameter to the actual size of the buffer that was used. If the specified size on input is greater than zero but less than the required size, you should not rely on the returned size to reallocate the buffer.

[in] dwFlags

Format of the input and output counter values. You can specify one of the following values.

Value	Meaning
PDH_PATH_WBEM_RESULT	Converts a PDH path to the WMI class and property name format.
PDH_PATH_WBEM_INPUT	Converts the WMI class and property name to a PDH path.
0	Returns the path in the PDH format, for example, \\computer\object(parent/instance#index)\counter.

Return value

If the function succeeds, it returns ERROR_SUCCESS.

If the function fails, the return value is a system error code or a PDH error code. The following are possible values.

Return code	Description
PDH_MORE_DATA	The szFullPathBuffer buffer is too small to contain the counter name. This return value is expected if pcchBufferSize is zero on input. If the specified size on input is greater than zero but less than the required size, you should not rely on the returned size to reallocate the buffer.
PDH_INVALID_ARGUMENT	A parameter is not valid or is incorrectly formatted. For example, on some releases you could receive this error if the specified size on input is greater than zero but less than the required size.

Remarks

You should call this function twice, the first time to get the required buffer size (set szFullPathBuffer to NULL and pcchBufferSize to 0), and the second time to get the data.

Note

The pdh.h header defines PdhMakeCounterPath as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	pdh.h
Library	Pdh.lib
DLL	Pdh.dll