UsbQueryNumberDevices: Difference between revisions
added parameter descriptions and example code |
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==Related Functions== | ==Related Functions== | ||
* [[UsbQueryDeviceReport]] | |||
* [[UsbQueryDeviceInfo]] | |||
* [[UsbOpen]] | |||
[[Category:USBCalls]] | [[Category:USBCalls]] | ||
Revision as of 17:20, 12 February 2017
Description
Obtains the total number of currently attached USB devices.
Syntax
ulrc = UsbQueryNumberDevices(pulNumDev)
Parameters
- pulNumDev
- the address of the variable to receive the Total Number.
Return Code
0x0000 - NO_ERROR
Errors
0x0057 - ERROR_INVALID_PARAMETER 0x1B58 - USB_NOT_INIT 0xFF13 - ERROR_I24_INVALID_PARAMETER 0xFF1F - ERROR_GEN_FAILURE 0xFF57 - ERROR_INVALID_PARAMETER
Remarks
Example Code
//Code Snippet - UsbQueryNumberDevices
{
APIRET ulrc;
PULONG pulNumDev;
ULONG ulNumDev;
pulNumDev = &ulNumDev;
ulrc = UsbQueryNumberDevices(pulNumDev);
printf("\nUsbQueryNumberDevices - ulrc: 0x%04X (%hu)",ulrc,ulrc);
if (!ulrc) //success
{
printf(" - NumberDevices: %hu",ulNumDev);
}
}