<!--
{
  "availability" : [
    "DriverKit: -",
    "iOS: -",
    "iPadOS: -",
    "macOS: -"
  ],
  "documentType" : "symbol",
  "framework" : "DriverKit",
  "identifier" : "/documentation/DriverKit/IOUserClientMethodDispatch/checkScalarInputCount",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "DriverKit"
    ],
    "preciseIdentifier" : "c:@S@IOUserClientMethodDispatch@FI@checkScalarInputCount"
  },
  "title" : "checkScalarInputCount"
}
-->

# checkScalarInputCount

The expected number of scalar inputs.

```
uint32_t checkScalarInputCount;
```

## Discussion

If the value of this field is [`kIOUserClientVariableStructureSize`](/documentation/DriverKit/kIOUserClientVariableStructureSize), ignore the value of the [`scalarInputCount`](/documentation/DriverKit/IOUserClientMethodArguments/scalarInputCount) field. For all other values, the value in this property must equal the value in the [`scalarInputCount`](/documentation/DriverKit/IOUserClientMethodArguments/scalarInputCount) field of the [`IOUserClientMethodArguments`](/documentation/DriverKit/IOUserClientMethodArguments) structure.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)