C# Signature:

[DllImport("kernel32.dll", SetLastError=true)]
public static extern uint PackageFamilyNameFromId( PACKAGE_ID packageId, ref uint packageFamilyNameLength, StringBuilder packageFamilyName );

User-Defined Types:

PACKAGE_ID

Tips & Tricks:

Call the function with packageFamilyName = NULL to get the required buffer size.

Sample Code:

  var packageId = new PACKAGE_ID { name = "Package Name", publisher = "CN=MyPublisher" };
  uint packageFamilyNameLength = 0;
  //First get the length of the Package Name -> Pass NULL as Output Buffer
  if ( PackageFamilyNameFromId( packageId, ref packageFamilyNameLength, null ) == 122 ) //ERROR_INSUFFICIENT_BUFFER
  {
    var packageFamilyNameBuilder = new StringBuilder((int)packageFamilyNameLength);
    if ( PackageFamilyNameFromId( packageId, ref packageFamilyNameLength, packageFamilyNameBuilder ) == 0 )
    {
      Console.WriteLine( "Package Family Name: " + packageFamilyNameBuilder.ToString() );
    }
  }