PdhGetFormattedCounterArrayA function

Returns an array of formatted counter values. Use this function when you want to format the counter values of a counter that contains a wildcard character for the instance name.

Syntax

PDH_FUNCTION PdhGetFormattedCounterArrayA(
  PDH_HCOUNTER                 hCounter,
  DWORD                        dwFormat,
  LPDWORD                      lpdwBufferSize,
  LPDWORD                      lpdwItemCount,
  PPDH_FMT_COUNTERVALUE_ITEM_A ItemBuffer
);

Parameters

hCounter

Handle to the counter whose current value you want to format. The PdhAddCounter function returns this handle.

dwFormat

Determines the data type of the formatted value. Specify one of the following values.

Value Meaning
PDH_FMT_DOUBLE
Return data as a double-precision floating point real.
PDH_FMT_LARGE
Return data as a 64-bit integer.
PDH_FMT_LONG
Return data as a long integer.
 

You can use the bitwise inclusive OR operator (|) to combine the data type with one of the following scaling factors.

Value Meaning
PDH_FMT_NOSCALE
Do not apply the counter's default scaling factor.
PDH_FMT_NOCAP100
Counter values greater than 100 (for example, counter values measuring the processor load on multiprocessor computers) will not be reset to 100. The default behavior is that counter values are capped at a value of 100.
PDH_FMT_1000
Multiply the actual value by 1,000.

lpdwBufferSize

Size of the ItemBuffer buffer, in bytes. 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.

lpdwItemCount

Number of counter values in the ItemBuffer buffer.

ItemBuffer

Caller-allocated buffer that receives an array of PDH_FMT_COUNTERVALUE_ITEM structures; the structures contain the counter values. Set to NULL if lpdwBufferSize is zero.

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 ItemBuffer buffer is not large enough to contain the object name. This return value is expected if lpdwBufferSize 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.
PDH_INVALID_HANDLE
The counter handle is not valid.

Remarks

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

The data for the counter is locked for the duration of the call to PdhGetFormattedCounterArray to prevent any changes during the processing of the call.

Examples

The following example shows how to use this function.


#include <windows.h>
#include <stdio.h>
#include <pdh.h>
#include <pdhmsg.h>

#pragma comment(lib, "pdh.lib")

CONST PWSTR COUNTER_PATH = L"\\Processor(*)\\% Processor Time";
CONST ULONG SAMPLE_INTERVAL_MS = 1000;

void main()
{
    PDH_HQUERY hQuery = NULL;
    PDH_STATUS status = ERROR_SUCCESS;
    PDH_HCOUNTER hCounter = NULL;   
    DWORD dwBufferSize = 0;         // Size of the pItems buffer
    DWORD dwItemCount = 0;          // Number of items in the pItems buffer
    PDH_FMT_COUNTERVALUE_ITEM *pItems = NULL;  // Array of PDH_FMT_COUNTERVALUE_ITEM structures

    if (status = PdhOpenQuery(NULL, 0, &hQuery))
    {
        wprintf(L"PdhOpenQuery failed with 0x%x.\n", status);
        goto cleanup;
    }

    // Specify a counter object with a wildcard for the instance.
    if (status = PdhAddCounter(hQuery, COUNTER_PATH, 0, &hCounter))
    {
        wprintf(L"PdhAddCounter failed with 0x%x.\n", status);
        goto cleanup;
    }

    // Some counters need two sample in order to format a value, so
    // make this call to get the first value before entering the loop.
    if (status = PdhCollectQueryData(hQuery))
    {
        wprintf(L"PdhCollectQueryData failed with 0x%x.\n", status);
        goto cleanup;
    }

    for (int i = 0; i < 10; i++)
    {
        Sleep(SAMPLE_INTERVAL_MS);

        if (status = PdhCollectQueryData(hQuery))
        {
            wprintf(L"PdhCollectQueryData failed with 0x%x.\n", status);
            goto cleanup;
        }

        // Get the required size of the pItems buffer.
        status = PdhGetFormattedCounterArray(hCounter, PDH_FMT_DOUBLE, &dwBufferSize, &dwItemCount, pItems);
        if (PDH_MORE_DATA == status)
        {
            pItems = (PDH_FMT_COUNTERVALUE_ITEM *) malloc(dwBufferSize);
            if (pItems)
            {
                status = PdhGetFormattedCounterArray(hCounter, PDH_FMT_DOUBLE, &dwBufferSize, &dwItemCount, pItems);
                if (ERROR_SUCCESS == status)
                {
                    // Loop through the array and print the instance name and counter value.
                    for (DWORD i = 0; i < dwItemCount; i++)
                    {
                        wprintf(L"counter: %s, value %.20g\n", pItems[i].szName, pItems[i].FmtValue.doubleValue);
                    }
                }
                else
                {
                    wprintf(L"Second PdhGetFormattedCounterArray call failed with 0x%x.\n", status);
                    goto cleanup;
                }

                free(pItems);
                pItems = NULL;
                dwBufferSize = dwItemCount = 0;
            }
            else
            {
                wprintf(L"malloc for PdhGetFormattedCounterArray failed.\n");
                goto cleanup;
            }
        }
        else
        {
            wprintf(L"PdhGetFormattedCounterArray failed with 0x%x.\n", status);
            goto cleanup;
        }
    }

cleanup:

    if (pItems)
        free(pItems);

    if (hQuery)
        PdhCloseQuery(hQuery); // Closes all counter handles and the query handle
}

Requirements

   
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

See also

PDH_FMT_COUNTERVALUE_ITEM

PdhAddCounter

PdhGetFormattedCounterValue

PdhGetRawCounterArray

PdhGetRawCounterValue