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  • USB Hub and Ubuntu

    - by aserwin
    I have a powered 7 port hub connected to my Ubuntu box and it does nothing. The devices (zip drive and web cam) work direct, but aren't recognized through the hub. This worked fine in Windows 7. I can't prove it is the OS because this is a new motherboard and processor. Any advice? EDIT : Output from lsusb -v Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ehci_hcd iProduct 2 EHCI Host Controller iSerial 1 0000:00:12.2 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 5 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0503 highspeed power enable connect Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Device Status: 0x0001 Self Powered Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ehci_hcd iProduct 2 EHCI Host Controller iSerial 1 0000:00:13.2 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 5 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Device Status: 0x0001 Self Powered Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ehci_hcd iProduct 2 EHCI Host Controller iSerial 1 0000:00:16.2 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 4 wHubCharacteristic 0x000a No power switching (usb 1.0) Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Device Status: 0x0001 Self Powered Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0001 1.1 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ohci_hcd iProduct 2 OHCI Host Controller iSerial 1 0000:00:12.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 255 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 5 wHubCharacteristic 0x0002 No power switching (usb 1.0) Ganged overcurrent protection bPwrOn2PwrGood 2 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Device Status: 0x0001 Self Powered Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0001 1.1 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ohci_hcd iProduct 2 OHCI Host Controller iSerial 1 0000:00:13.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 255 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 5 wHubCharacteristic 0x0002 No power switching (usb 1.0) Ganged overcurrent protection bPwrOn2PwrGood 2 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Port 5: 0000.0100 power Device Status: 0x0001 Self Powered Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0001 1.1 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ohci_hcd iProduct 2 OHCI Host Controller iSerial 1 0000:00:14.5 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 255 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 2 wHubCharacteristic 0x0002 No power switching (usb 1.0) Ganged overcurrent protection bPwrOn2PwrGood 2 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Device Status: 0x0001 Self Powered Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0001 1.1 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic ohci_hcd iProduct 2 OHCI Host Controller iSerial 1 0000:00:16.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 255 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 4 wHubCharacteristic 0x0002 No power switching (usb 1.0) Ganged overcurrent protection bPwrOn2PwrGood 2 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0303 lowspeed power enable connect Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0100 power Device Status: 0x0001 Self Powered Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 1 Single TT bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0002 2.0 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic xhci_hcd iProduct 2 xHCI Host Controller iSerial 1 0000:02:00.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 2 wHubCharacteristic 0x0009 Per-port power switching Per-port overcurrent protection TT think time 8 FS bits bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Device Status: 0x0001 Self Powered Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 3.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 3 bMaxPacketSize0 9 idVendor 0x1d6b Linux Foundation idProduct 0x0003 3.0 root hub bcdDevice 3.02 iManufacturer 3 Linux 3.2.0-32-generic xhci_hcd iProduct 2 xHCI Host Controller iSerial 1 0000:02:00.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 31 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0004 1x 4 bytes bInterval 12 bMaxBurst 0 Hub Descriptor: bLength 12 bDescriptorType 42 nNbrPorts 2 wHubCharacteristic 0x0009 Per-port power switching Per-port overcurrent protection bPwrOn2PwrGood 10 * 2 milli seconds bHubContrCurrent 0 milli Ampere bHubDecLat 0.0 micro seconds wHubDelay 0 nano seconds DeviceRemovable 0x00 Hub Port Status: Port 1: 0000.02a0 5Gbps power Rx.Detect Port 2: 0000.02a0 5Gbps power Rx.Detect Binary Object Store Descriptor: bLength 5 bDescriptorType 15 wTotalLength 15 bNumDeviceCaps 1 SuperSpeed USB Device Capability: bLength 10 bDescriptorType 16 bDevCapabilityType 3 bmAttributes 0x00 Latency Tolerance Messages (LTM) Supported wSpeedsSupported 0x0008 Device can operate at SuperSpeed (5Gbps) bFunctionalitySupport 3 Lowest fully-functional device speed is SuperSpeed (5Gbps) bU1DevExitLat 3 micro seconds bU2DevExitLat 2047 micro seconds Device Status: 0x0001 Self Powered Bus 001 Device 002: ID 04a9:1709 Canon, Inc. PIXMA MP150 Scanner Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x04a9 Canon, Inc. idProduct 0x1709 PIXMA MP150 Scanner bcdDevice 1.08 iManufacturer 1 Canon iProduct 2 MP150 iSerial 3 20BC24 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 62 bNumInterfaces 2 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xc0 Self Powered MaxPower 2mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 3 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 255 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x07 EP 7 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x88 EP 8 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x89 EP 9 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 11 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 7 Printer bInterfaceSubClass 1 Printer bInterfaceProtocol 2 Bidirectional iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Bus 007 Device 002: ID 046d:c517 Logitech, Inc. LX710 Cordless Desktop Laser Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 8 idVendor 0x046d Logitech, Inc. idProduct 0xc517 LX710 Cordless Desktop Laser bcdDevice 38.10 iManufacturer 1 Logitech iProduct 2 USB Receiver iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 59 bNumInterfaces 2 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xa0 (Bus Powered) Remote Wakeup MaxPower 98mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 3 Human Interface Device bInterfaceSubClass 1 Boot Interface Subclass bInterfaceProtocol 1 Keyboard iInterface 0 HID Device Descriptor: bLength 9 bDescriptorType 33 bcdHID 1.10 bCountryCode 0 Not supported bNumDescriptors 1 bDescriptorType 34 Report wDescriptorLength 59 Report Descriptors: ** UNAVAILABLE ** Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 10 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 3 Human Interface Device bInterfaceSubClass 1 Boot Interface Subclass bInterfaceProtocol 2 Mouse iInterface 0 HID Device Descriptor: bLength 9 bDescriptorType 33 bcdHID 1.10 bCountryCode 0 Not supported bNumDescriptors 1 bDescriptorType 34 Report wDescriptorLength 177 Report Descriptors: ** UNAVAILABLE ** Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0008 1x 8 bytes bInterval 10 Device Status: 0x0000 (Bus Powered) This is with the powered hub plugged in.

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  • The Return Of __FILE__ And __LINE__ In .NET 4.5

    - by Alois Kraus
    Good things are hard to kill. One of the most useful predefined compiler macros in C/C++ were __FILE__ and __LINE__ which do expand to the compilation units file name and line number where this value is encountered by the compiler. After 4.5 versions of .NET we are on par with C/C++ again. It is of course not a simple compiler expandable macro it is an attribute but it does serve exactly the same purpose. Now we do get CallerLineNumberAttribute  == __LINE__ CallerFilePathAttribute        == __FILE__ CallerMemberNameAttribute  == __FUNCTION__ (MSVC Extension)   The most important one is CallerMemberNameAttribute which is very useful to implement the INotifyPropertyChanged interface without the need to hard code the name of the property anymore. Now you can simply decorate your change method with the new CallerMemberName attribute and you get the property name as string directly inserted by the C# compiler at compile time.   public string UserName { get { return _userName; } set { _userName=value; RaisePropertyChanged(); // no more RaisePropertyChanged(“UserName”)! } } protected void RaisePropertyChanged([CallerMemberName] string member = "") { var copy = PropertyChanged; if(copy != null) { copy(new PropertyChangedEventArgs(this, member)); } } Nice and handy. This was obviously the prime reason to implement this feature in the C# 5.0 compiler. You can repurpose this feature for tracing to get your hands on the method name of your caller along other stuff very fast now. All infos are added during compile time which is much faster than other approaches like walking the stack. The example on MSDN shows the usage of this attribute with an example public static void TraceMessage(string message, [CallerMemberName] string memberName = "", [CallerFilePath] string sourceFilePath = "", [CallerLineNumber] int sourceLineNumber = 0) { Console.WriteLine("Hi {0} {1} {2}({3})", message, memberName, sourceFilePath, sourceLineNumber); }   When I do think of tracing I do usually want to have a API which allows me to Trace method enter and leave Trace messages with a severity like Info, Warning, Error When I do print a trace message it is very useful to print out method and type name as well. So your API must either be able to pass the method and type name as strings or extract it automatically via walking back one Stackframe and fetch the infos from there. The first glaring deficiency is that there is no CallerTypeAttribute yet because the C# compiler team was not satisfied with its performance.   A usable Trace Api might therefore look like   enum TraceTypes { None = 0, EnterLeave = 1 << 0, Info = 1 << 1, Warn = 1 << 2, Error = 1 << 3 } class Tracer : IDisposable { string Type; string Method; public Tracer(string type, string method) { Type = type; Method = method; if (IsEnabled(TraceTypes.EnterLeave,Type, Method)) { } } private bool IsEnabled(TraceTypes traceTypes, string Type, string Method) { // Do checking here if tracing is enabled return false; } public void Info(string fmt, params object[] args) { } public void Warn(string fmt, params object[] args) { } public void Error(string fmt, params object[] args) { } public static void Info(string type, string method, string fmt, params object[] args) { } public static void Warn(string type, string method, string fmt, params object[] args) { } public static void Error(string type, string method, string fmt, params object[] args) { } public void Dispose() { // trace method leave } } This minimal trace API is very fast but hard to maintain since you need to pass in the type and method name as hard coded strings which can change from time to time. But now we have at least CallerMemberName to rid of the explicit method parameter right? Not really. Since any acceptable usable trace Api should have a method signature like Tracexxx(… string fmt, params [] object args) we not able to add additional optional parameters after the args array. If we would put it before the format string we would need to make it optional as well which would mean the compiler would need to figure out what our trace message and arguments are (not likely) or we would need to specify everything explicitly just like before . There are ways around this by providing a myriad of overloads which in the end are routed to the very same method but that is ugly. I am not sure if nobody inside MS agrees that the above API is reasonable to have or (more likely) that the whole talk about you can use this feature for diagnostic purposes was not a core feature at all but a simple byproduct of making the life of INotifyPropertyChanged implementers easier. A way around this would be to allow for variable argument arrays after the params keyword another set of optional arguments which are always filled by the compiler but I do not know if this is an easy one. The thing I am missing much more is the not provided CallerType attribute. But not in the way you would think of. In the API above I did add some filtering based on method and type to stay as fast as possible for types where tracing is not enabled at all. It should be no more expensive than an additional method call and a bool variable check if tracing for this type is enabled at all. The data is tightly bound to the calling type and method and should therefore become part of the static type instance. Since extending the CLR type system for tracing is not something I do expect to happen I have come up with an alternative approach which allows me basically to attach run time data to any existing type object in super fast way. The key to success is the usage of generics.   class Tracer<T> : IDisposable { string Method; public Tracer(string method) { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public void Dispose() { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public static void Info(string fmt, params object[] args) { } /// <summary> /// Every type gets its own instance with a fresh set of variables to describe the /// current filter status. /// </summary> /// <typeparam name="T"></typeparam> internal class TraceData<UsingType> { internal static TraceData<UsingType> Instance = new TraceData<UsingType>(); public bool IsInitialized = false; // flag if we need to reinit the trace data in case of reconfigured trace settings at runtime public TraceTypes Enabled = TraceTypes.None; // Enabled trace levels for this type } } We do not need to pass the type as string or Type object to the trace Api. Instead we define a generic Api that accepts the using type as generic parameter. Then we can create a TraceData static instance which is due to the nature of generics a fresh instance for every new type parameter. My tests on my home machine have shown that this approach is as fast as a simple bool flag check. If you have an application with many types using tracing you do not want to bring the app down by simply enabling tracing for one special rarely used type. The trace filter performance for the types which are not enabled must be therefore the fasted code path. This approach has the nice side effect that if you store the TraceData instances in one global list you can reconfigure tracing at runtime safely by simply setting the IsInitialized flag to false. A similar effect can be achieved with a global static Dictionary<Type,TraceData> object but big hash tables have random memory access semantics which is bad for cache locality and you always need to pay for the lookup which involves hash code generation, equality check and an indexed array access. The generic version is wicked fast and allows you to add more features to your tracing Api with minimal perf overhead. But it is cumbersome to write the generic type argument always explicitly and worse if you do refactor code and move parts of it to other classes it might be that you cannot configure tracing correctly. I would like therefore to decorate my type with an attribute [CallerType] class Tracer<T> : IDisposable to tell the compiler to fill in the generic type argument automatically. class Program { static void Main(string[] args) { using (var t = new Tracer()) // equivalent to new Tracer<Program>() { That would be really useful and super fast since you do not need to pass any type object around but you do have full type infos at hand. This change would be breaking if another non generic type exists in the same namespace where now the generic counterpart would be preferred. But this is an acceptable risk in my opinion since you can today already get conflicts if two generic types of the same name are defined in different namespaces. This would be only a variation of this issue. When you do think about this further you can add more features like to trace the exception in your Dispose method if the method is left with an exception with that little trick I did write some time ago. You can think of tracing as a super fast and configurable switch to write data to an output destination or to execute alternative actions. With such an infrastructure you can e.g. Reconfigure tracing at run time. Take a memory dump when a specific method is left with a specific exception. Throw an exception when a specific trace statement is hit (useful for testing error conditions). Execute a passed delegate which e.g. dumps additional state when enabled. Write data to an in memory ring buffer and dump it when specific events do occur (e.g. method is left with an exception, triggered from outside). Write data to an output device. …. This stuff is really useful to have when your code is in production on a mission critical server and you need to find the root cause of sporadic crashes of your application. It could be a buggy graphics card driver which throws access violations into your application (ok with .NET 4 not anymore except if you enable a compatibility flag) where you would like to have a minidump or you have reached after two weeks of operation a state where you need a full memory dump at a specific point in time in the middle of an transaction. At my older machine I do get with this super fast approach 50 million traces/s when tracing is disabled. When I do know that tracing is enabled for this type I can walk the stack by using StackFrameHelper.GetStackFramesInternal to check further if a specific action or output device is configured for this method which is about 2-3 times faster than the regular StackTrace class. Even with one String.Format I am down to 3 million traces/s so performance is not so important anymore since I do want to do something now. The CallerMemberName feature of the C# 5 compiler is nice but I would have preferred to get direct access to the MethodHandle and not to the stringified version of it. But I really would like to see a CallerType attribute implemented to fill in the generic type argument of the call site to augment the static CLR type data with run time data.

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  • I get Get-WmiObject : Generic Failure error on an XP Machine. What needs to be done to get rid of this?

    - by steeluser
    I am trying make an uninstall app which removes an application X on a regular basis. The starting point to access applications installed in a Windows machine is through retrieving them from a WMI Class called Win32_Product. But when I run the basic command like this, I get the below error. I have searched technet and SO, but either their workarounds did not work for me or were too technical in detail which did not make sense to me. Please help. SO Link ps$ Get-WmiObject -class win32_product IdentifyingNumber : {09959E11-AD5D-408E-96AF-E3346954D6B8} Name : Shared Add-in Extensibility Update for Microsoft .NET Framework 2.0 (KB908002) Vendor : Microsoft Version : 1.0.0 Caption : Shared Add-in Extensibility Update for Microsoft .NET Framework 2.0 (KB908002) Get-WmiObject : Generic failure At line:1 char:14 + Get-WmiObject <<<< -class win32_product + CategoryInfo : InvalidOperation: (:) [Get-WmiObject], ManagementException + FullyQualifiedErrorId : GetWMIManagementException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

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  • Subterranean IL: Constructor constraints

    - by Simon Cooper
    The constructor generic constraint is a slightly wierd one. The ECMA specification simply states that it: constrains [the type] to being a concrete reference type (i.e., not abstract) that has a public constructor taking no arguments (the default constructor), or to being a value type. There seems to be no reference within the spec to how you actually create an instance of a generic type with such a constraint. In non-generic methods, the normal way of creating an instance of a class is quite different to initializing an instance of a value type. For a reference type, you use newobj: newobj instance void IncrementableClass::.ctor() and for value types, you need to use initobj: .locals init ( valuetype IncrementableStruct s1 ) ldloca 0 initobj IncrementableStruct But, for a generic method, we need a consistent method that would work equally well for reference or value types. Activator.CreateInstance<T> To solve this problem the CLR designers could have chosen to create something similar to the constrained. prefix; if T is a value type, call initobj, and if it is a reference type, call newobj instance void !!0::.ctor(). However, this solution is much more heavyweight than constrained callvirt. The newobj call is encoded in the assembly using a simple reference to a row in a metadata table. This encoding is no longer valid for a call to !!0::.ctor(), as different constructor methods occupy different rows in the metadata tables. Furthermore, constructors aren't virtual, so we would have to somehow do a dynamic lookup to the correct method at runtime without using a MethodTable, something which is completely new to the CLR. Trying to do this in IL results in the following verification error: newobj instance void !!0::.ctor() [IL]: Error: Unable to resolve token. This is where Activator.CreateInstance<T> comes in. We can call this method to return us a new T, and make the whole issue Somebody Else's Problem. CreateInstance does all the dynamic method lookup for us, and returns us a new instance of the correct reference or value type (strangely enough, Activator.CreateInstance<T> does not itself have a .ctor constraint on its generic parameter): .method private static !!0 CreateInstance<.ctor T>() { call !!0 [mscorlib]System.Activator::CreateInstance<!!0>() ret } Going further: compiler enhancements Although this method works perfectly well for solving the problem, the C# compiler goes one step further. If you decompile the C# version of the CreateInstance method above: private static T CreateInstance() where T : new() { return new T(); } what you actually get is this (edited slightly for space & clarity): .method private static !!T CreateInstance<.ctor T>() { .locals init ( [0] !!T CS$0$0000, [1] !!T CS$0$0001 ) DetectValueType: ldloca.s 0 initobj !!T ldloc.0 box !!T brfalse.s CreateInstance CreateValueType: ldloca.s 1 initobj !!T ldloc.1 ret CreateInstance: call !!0 [mscorlib]System.Activator::CreateInstance<T>() ret } What on earth is going on here? Looking closer, it's actually quite a clever performance optimization around value types. So, lets dissect this code to see what it does. The CreateValueType and CreateInstance sections should be fairly self-explanatory; using initobj for value types, and Activator.CreateInstance for reference types. How does the DetectValueType section work? First, the stack transition for value types: ldloca.s 0 // &[!!T(uninitialized)] initobj !!T // ldloc.0 // !!T box !!T // O[!!T] brfalse.s // branch not taken When the brfalse.s is hit, the top stack entry is a non-null reference to a boxed !!T, so execution continues to to the CreateValueType section. What about when !!T is a reference type? Remember, the 'default' value of an object reference (type O) is zero, or null. ldloca.s 0 // &[!!T(null)] initobj !!T // ldloc.0 // null box !!T // null brfalse.s // branch taken Because box on a reference type is a no-op, the top of the stack at the brfalse.s is null, and so the branch to CreateInstance is taken. For reference types, Activator.CreateInstance is called which does the full dynamic lookup using reflection. For value types, a simple initobj is called, which is far faster, and also eliminates the unboxing that Activator.CreateInstance has to perform for value types. However, this is strictly a performance optimization; Activator.CreateInstance<T> works for value types as well as reference types. Next... That concludes the initial premise of the Subterranean IL series; to cover the details of generic methods and generic code in IL. I've got a few other ideas about where to go next; however, if anyone has any itching questions, suggestions, or things you've always wondered about IL, do let me know.

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  • Left Join in Subsonic 3

    - by user303187
    I'm trying to do a left join in subsonic 3 using linq but it doesn't seem to work, I get a big error. var post = from p in Post.All() join q in Quote.All() on p.ID equals q.PostID into pq where p.ID == id.Value from qt in pq.DefaultIfEmpty() select new {p, qt}; I'm using subsonic 3, latest GIT version from Rob, but I'm getting an error, see below, when I try a left join. I have searched but I didn't found any solution. Can anyone explain to me why the error and how to fix it? Thanks Expression of type 'System.Collections.Generic.IEnumerable1[GetAQuote.Post]' cannot be used for parameter of type 'System.Linq.IQueryable1[GetAQuote.Post]' of method 'System.Linq.IQueryable1[<>f__AnonymousType221[GetAQuote.Post], System.Collections.Generic.IEnumerable1%5BGetAQuote.Quote%5D, System.Linq.Expressions.Expression1[System.Func2%5BGetAQuote.Post,System.Int32%5D%5D, System.Linq.Expressions.Expression1[System.Func2%5BGetAQuote.Quote,System.Int32%5D%5D, System.Linq.Expressions.Expression1[System.Func3%5BGetAQuote.Post,System.Collections.Generic.IEnumerable1[GetAQuote.Quote],<>f__AnonymousType22%5BGetAQuote.Post,System.Collections.Generic.IEnumerable1%5BGetAQuote.Quote%5D%5D%5D%5D"GetAQuote.Post,System.Collections.Generic.IEnumerable1[GetAQuote.Quote]]] GroupJoin[Post,Quote,Int32,<f__AnonymousType22'`

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  • Why enumerator structs are a really bad idea

    - by Simon Cooper
    If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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  • Unable to boot: Missing Operating system

    - by Vivek S Panicker
    i had installed Ubuntu 11.10 along with the another Ubuntu 11.10 which already installed in my netbook. Later I formatted the partition I newly installed. Next time when I boot it went to Grub Rescue menu. I boot my system again with Ubuntu USB stick, Then I installed Boot repair package in USB and restored MBR and GRUB menu in hard disk. Now when I am restarting, I am getting a message Missing operating system, press any key to continue. Can somebody help me on this? Below is the output for sudo fdisk -l omitting empty partition (7) Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00058a60 Device Boot Start End Blocks Id System /dev/sda1 * 2048 204072287 102035120 83 Linux /dev/sda2 204072958 312580095 54253569 5 Extended /dev/sda5 310507520 312580095 1036288 82 Linux swap / Solaris /dev/sda6 308432896 310503423 1035264 82 Linux swap / Solaris Partition table entries are not in disk order Disk /dev/sdb: 4006 MB, 4006608896 bytes 124 heads, 62 sectors/track, 1017 cylinders, total 7825408 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0004d3df Device Boot Start End Blocks Id System /dev/sdb1 * 62 7818695 3909317 b W95 FAT32 Below is the output for sudo blkid /dev/loop0: TYPE="squashfs" /dev/loop1: LABEL="casper-rw" UUID="533defb1-f073-254a-b46f-7ca0ac1f4e0c" TYPE="ext2" /dev/sda1: LABEL="Ubuntu" UUID="6a141040-3ba8-457a-9de5-ad06e6057084" TYPE="ext4" /dev/sda5: UUID="3a7f62d6-9c65-4d12-a3b6-5d62b9710f7d" TYPE="swap" /dev/sda6: UUID="274da115-cec2-4418-a1af-88fe921e3670" TYPE="swap" /dev/sdb1: LABEL="PENDRIVE" UUID="EC22-6BE4" TYPE="vfat" File /boot/grub/grub.cfg # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=10 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux /boot/vmlinuz-3.0.0-12-generic root=UUID=6a141040-3ba8-457a-9de5-ad06e6057084 ro quiet splash vt.handoff=7 initrd /boot/initrd.img-3.0.0-12-generic } menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 echo 'Loading Linux 3.0.0-12-generic ...' linux /boot/vmlinuz-3.0.0-12-generic root=UUID=6a141040-3ba8-457a-9de5-ad06e6057084 ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.0.0-12-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 6a141040-3ba8-457a-9de5-ad06e6057084 linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ###

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  • Can't see my partitions after grub recovery

    - by dimbo
    I stupidly inserted the windows CD into my dual boot Ubuntu 11.10 / windows xp system. I just wanted to see if I could install windows on my external usb HD, but didn't actually go ahead with the install. It seems like the windows CD messed up my MBR and I had to use boot-repair and the ubuntu 11.10 live CD to gain access to ubuntu again. It seems to boot up a little differently (slower) but works. However, I now cant see any of my partitions in nautilus (there are 3). When I open gparted, it just shows my whole hard drive as unallocated (I know it has a windows partition that works and my ubuntu partition that I am using now). If I insert a usb pen, it is also not visible in nautilus but in gparted shows up as a FAT32 partition (which is correct although I cannot access it). sudo fdisk -l gives the following : demian@dimbo-TP:~$ sudo fdisk -l [sudo] password for demian: omitting empty partition (5) Disk /dev/sda: 320.1 GB, 320072933376 bytes 240 heads, 63 sectors/track, 41345 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x877b877b Device Boot Start End Blocks Id System /dev/sda1 * 63 63842309 31921123+ 7 HPFS/NTFS/exFAT /dev/sda2 63844350 133484084 34819867+ 5 Extended /dev/sda3 127636488 133484084 2923798+ 82 Linux swap / Solaris /dev/sda4 133484085 625137344 245826630 83 Linux /dev/sda5 63844352 123445247 29800448 83 Linux /dev/sda6 123447296 127635455 2094080 82 Linux swap / Solaris Disk /dev/sdb: 8100 MB, 8100249600 bytes 12 heads, 40 sectors/track, 32960 cylinders, total 15820800 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc3072e18 Device Boot Start End Blocks Id System /dev/sdb1 * 5992 15820799 7907404 c W95 FAT32 (LBA) Here is my grub.conf file. Like I said before, I had to use the 'boot-repair' utility with the live cd to get grub working again. I think that this utility maybe created a new grub for me because the startup is definitely not the same. The screen goes blank for a while, and then the ubuntu loading dots come up for a brief moment (instead of during the whole startup process) before the dektop is displayed. Anyway : # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=10 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro quiet splash vt.handoff=7 initrd /boot/initrd.img-3.0.0-12-generic } menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a echo 'Loading Linux 3.0.0-12-generic ...' linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.0.0-12-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Microsoft Windows XP Professional (on /dev/sda1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 72A89361A89322A1 drivemap -s (hd0) ${root} chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### How can I get things back to normal. Thanks, Demian.

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  • Hi i have a c programming doubt in the implementation of hash table?

    - by aks
    Hi i have a c programming doubt in the implementation of hash table? I have implemented the hash table for storing some strings? I am having problem while dealing with hash collisons. I am following chaining link-list approach to overcome the same? But, somehow my code is behaving differently. I am not able to debug the same? Can somebody help? This is what i am facing: Say first time, i insert a string called gaur. My hash map calculates the index as 0 and inserts the string successfully. However, when another string whose hash map also when calculates turns out to be 0, my previous value gets overrridden i.e. gaur will be replaced by new string. This is my code: struct list { char *string; struct list *next; }; struct hash_table { int size; /* the size of the table */ struct list **table; /* the table elements */ }; struct hash_table *create_hash_table(int size) { struct hash_table *new_table; int i; if (size<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the table structure */ if ((new_table = malloc(sizeof(struct hash_table))) == NULL) { return NULL; } /* Attempt to allocate memory for the table itself */ if ((new_table->table = malloc(sizeof(struct list *) * size)) == NULL) { return NULL; } /* Initialize the elements of the table */ for(i=0; i<size; i++) new_table->table[i] = '\0'; /* Set the table's size */ new_table->size = size; return new_table; } unsigned int hash(struct hash_table *hashtable, char *str) { unsigned int hashval = 0; int i = 0; for(; *str != '\0'; str++) { hashval += str[i]; i++; } return (hashval % hashtable->size); } struct list *lookup_string(struct hash_table *hashtable, char *str) { printf("\n enters in lookup_string \n"); struct list * new_list; unsigned int hashval = hash(hashtable, str); /* Go to the correct list based on the hash value and see if str is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ for(new_list = hashtable->table[hashval]; new_list != NULL;new_list = new_list->next) { if (strcmp(str, new_list->string) == 0) return new_list; } printf("\n returns NULL in lookup_string \n"); return NULL; } int add_string(struct hash_table *hashtable, char *str) { printf("\n enters in add_string \n"); struct list *new_list; struct list *current_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d", hashval); /* Attempt to allocate memory for list */ if ((new_list = malloc(sizeof(struct list))) == NULL) { printf("\n enters here \n"); return 1; } /* Does item already exist? */ current_list = lookup_string(hashtable, str); if (current_list == NULL) { printf("\n DEBUG Purpose \n"); printf("\n NULL \n"); } /* item already exists, don't insert it again. */ if (current_list != NULL) { printf("\n Item already present...\n"); return 2; } /* Insert into list */ printf("\n Inserting...\n"); new_list->string = strdup(str); new_list->next = NULL; //new_list->next = hashtable->table[hashval]; if(hashtable->table[hashval] == NULL) { hashtable->table[hashval] = new_list; } else { struct list * temp_list = hashtable->table[hashval]; while(temp_list->next!=NULL) temp_list = temp_list->next; temp_list->next = new_list; hashtable->table[hashval] = new_list; } return 0; }

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  • How do I write a bash script to replace words in files and then rename files?

    - by Jason
    Hi All, I have a folder structure, as shown below: I need to create a bash script that does 4 things: It searches all the files in the generic directory and finds the string 'generic' and makes it into 'something' As above, but changes "GENERIC" to "SOMETHING" As above, but changes "Generic" to "Something" Renames any filename that has "generic" in it with "something" Right now I am doing this process manually by using the search and replace in net beans. I dont know much about bash scripting, but i'm sure this can be done. I'm thinking of something that I would run and it would take "Something" as the input. Where would I start? what functions should I use? overall guidance would be great. thanks. I am using Ubuntu 10.5 desktop edition.

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  • Silverlight Cream for January 30, 2011 - 2 -- #1038

    - by Dave Campbell
    In this Issue: Max Paulousky, Renuka Prasad, Ollie Riches, Jesse Liberty(-2-, -3-, -4-, -5-), Medusa M, John Papa, Beth Massi, and Joost van Schaik. Above the Fold: Silverlight: "Stop What You Are Doing And Learn About Reactive Programming" Jesse Liberty WP7: "Windows Phone Looping Selector for Digits " Max Paulousky Lightswitch: "How To Send HTML Email from a LightSwitch Application" Beth Massi Shoutouts: Shawn Wildermuch has niether GooNews for users of his cool WP7 app or or for the WP7 Marketplace in general: R.I.P. GooNews From SilverlightCream.com: Windows Phone Looping Selector for Digits Max Paulousky expanded on the Looping selector for some customization allowing him to display width/height metric measurement selectors... great job, Max! WP7 – How to Create a Simple Checked Listbox In Windows Phone 7 Renuka Prasad has the code for a nicely-working checked Listbox for WP7 on his blog... the post is the code... WP7Contrib: Network Connectivity Push Model Ollie Riches had a post last week that I'm just catching up to... about the 'push model' for network connectivity they produced in WP7 Contrib. Using the Camera in Windows Phone 7 Jesse Liberty has a bunch of posts up... I'm just going to bite the bullet and catch up! ... this 'From Scratch post 24 is all about the camera in your WP7 dev travails... and he makes it look so darned easy :) Linq and Fluent Programming Jesse Liberty's next post is 'From Scratch 25 and is all about Linq and Fluent Programming which started with a discussion at Codemash with Bill Wagner... wanna get a handle on fluent programming? ... check this out. Stop What You Are Doing And Learn About Reactive Programming Another item you might want to get your head around is Reactive Programming, or Rx... Jesse Liberty has a great post up discussing this, as his 'From Scratch post 26... good external links, and lots of commentary as well. Rx–Reactive Programming for Windows Phone Jesse Liberty's 'From Scratch 27 follows the previous on about Rx by taking the Rx show to the WP7 development arena. Want a solid Rx example... here ya go! Reactive Extensions–Observable Sequences are First Class Objects Finally catching up with Jesse Liberty (for now), I find this 'From Scratch number 28 which is again on Rx and WP7 dev, expanding on the example from the previous post by harnessing the power of Rx Localizing Silverlight applications Medusa M has a nice post up at dotnetslackers on localization in Silverlight. If you haven't had to do localization before, it can get to be a pain... understanding an article like this will get you part of the way to being pain-free. Silverlight TV 59: What Goes Into Baking Silverlight? Very cool presentation for those of you interested in the bits ... John Papa's Silverlight TV number 59 is up and he's chatting with Andy Rivas about the process followed getting the bits to us. How To Send HTML Email from a LightSwitch Application Beth Massi's latest Lightswitch post is on sending HTML Email via SMTP from Lightswitch, and then follows that up with sending Email via Outlook automation. ViewModel driven animations using the Visual State Manager, DataStateBehavior and Expression Blend After some good user feedback, Joost van Schaik decided to make some modifications to his WP7 app, and got involved in a Page Title collapse animation driven from the ViewModel. Check out the nice write-up, video, external links, and source... all good! Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • How to familiarize myself with Python

    - by Zel
    I am Python beginner. Started Python 1.5 months back. I downloaded the Python docs and read some part of the tutorial. I have been programming on codechef.com and solving problems of projecteuler. I am thinking of reading Introduction to algorithms and following this course on MIT opencourse ware as I haven't been getting much improvement in programming and I am wasting much time thinking just what should I do when faced with any programming problem. But I think that I still don't know the correct way to learn the language itself. Should I start the library reference or continue with Python tutorial? Is learning algorithms useful for language such as C and not so much for Python as it has "batteries included"? Are there some other resources for familiarization with the language and in general for learning to solve programming problems? Or do I need to just devote some more time?

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  • TechDays 2010: What’s New On C# 4.0

    - by Paulo Morgado
    I would like to thank those that attended my session at TechDays 2010 and I hope that I was able to pass the message of what’s new on C#. For those that didn’t attend (or did and want to review it), the presentation can be downloaded from here. Code samples can be downlaoded from here. Here’s a list of resources mentioned on the session: The evolution of C# The Evolution Of C# Covariance and contravariance  C# 4.0: Covariance And Contravariance In Generics Covariance And Contravariance In Generics Made Easy Covarince and Contravariance in Generics Exact rules for variance validity Events get a little overhaul in C# 4, Afterward: Effective Events Named and optional arguments  Named And Optional Arguments Alternative To Optional Arguments Named and Optional Arguments (C# Programming Guide) Dynamic programming  Dynamic Programming C# Proposal: Compile Time Static Checking Of Dynamic Objects Using Type dynamic (C# Programming Guide) Dynamic Language Runtime Overview COM Interop Improvements COM Interop Improvements Type Equivalence and Embedded Interop Types Conclusion Visual C# Developer Center Visual C# 2010 Samples C# Language Specification 4.0 .NET Reflector LINQPad

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  • April 2010 Meeting of Israel Dot Net Developers User Group (IDNDUG)

    - by Jackie Goldstein
    Note the special date of this meeting - Thursday April 29, 2010 The April 2010 meeting of the Israel Dot Net Developers User Group will be held on Thursday April 29, 2010 .   This meeting will focus on parallel programming – in general and the support in VS 2010.  Our speaker will be Asaf Shelly, a recognized expert in parallel programming. Abstract : (1) Parallel Programming in Microsoft's Environments. The fundamentals of Windows have always been parallel. Starting with message queues...(read more)

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  • Explain Model View Controller

    - by Channel72
    My experience with developing dynamic websites is limited mostly to Java servlets. I've used Tomcat to develop various Java servlets, and I wouldn't hesitate to say that I'm reasonably proficient with this technology, as well as with client-side HTML/CSS/Javascript for the front-end. When I think "dynamic website", I think: user requests a URL with a query string, server receives the query, and then proceeds to output HTML dynamically in order to respond to the query. This often involves communication with a database in order to fetch requested data for display. This is basically the idea behind the doGet method of a Java HttpServlet. But these days, I'm hearing more and more about newer frameworks such as Django and Ruby on Rails, all of which take advantage of the "Model View Controller" architecture. I've read various articles which explain MVC, but I'm having trouble really understanding the benefits. I understand that the general idea is to separate business logic from UI logic, but I fail to see how this is anything really different from normal web programming. Web programming, by it's very nature, forces you to separate business logic (back-end server-side programming) from UI programming (client-side HTML or Javascript), because the two exist in entirely different spheres of programming. Question: What does MVC offer over something like a Java servlet, and more importantly, what exactly is MVC and how is it different from what you would normally do to develop a dynamic website using a more traditional approach such as a Java servlet (or even something older like CGI). If possible, when explaining MVC, please provide an example which illustrates how MVC is applied to the web development process, and how it is beneficial.

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  • Math questions at a programmer interview?

    - by anon
    So I went to an interview at Samsung here in Dallas, Texas. The way the recruiter described the job, he didn't make it sound like it was too math-oriented. The job basically involved graphics programming and C++. Yes, math is implied in graphics programming, especially shaders, but I still wasn't expecting this... The whole interview lasted about an hour and a half and they asked me nothing but math-related questions. They didn't ask me a single programming question, which I found odd. About all they did was ask me how to write certain math routines as a C++ function, but that's about it. What about programming philosophy questions? Design patterns? Code-correctness? Constness? Exception safety? Thread safety? There are a zillion topics that they could have covered. But they didn't. The main concern I have is that they didn't ask any programming questions. This basically implies to me that any programmer who is good at math can get a job here, but they might put out terrible code. Of course, I think I bombed the interview because I haven't used any sort of linear algebra in about a year and I forget math easily if I haven't used it in practice for a while. Are any of my other fellow programmers out there this way? I'm a game programmer too, so this seems especially odd. The more I learn, the more old knowledge that gets "popped" out of my "stack" (memory). My question is: Does this interview seem suspicious? Is this a typical interview that large corporations have? During the interview they told me that Google's interview process is similar. They have multiple, consecutive interviews where the math problems get more advanced.

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  • Identifying Hard Drive as performance bottleneck for desktop machines

    - by Programming Hero
    I'm working in a development team where we all use laptops so we can work in multiple locations. These laptops are proving notoriously slow for development work, but at a glance they all look to have the specification for a much faster experience: CPU - Intel Core 2 Duo T7500 Memory - 2GB of RAM We all experience the biggest delays when the hard-drives are being accessed, particularly when swap-files are being thrashed. After doing a little bit of profile, a colleague discovered that our HDDs are seeing Read/Write speeds of about 10MB/sec. This seems abnormally low and we believe it the cause of the problem. Sensibly (though somewhat annoyingly) our business wont blow money on faster drives just to see if it fixes the problem; we need to illustrate this is definitely the problem and that buying some solid-state drives will make it go away. I need some way of showing how 90% of the system resources aren't being used over the course of a day, and that whenever there is utilization, it's all in HDD reads or writes. Are there any tools I could use to provide this information? Does it seem likely the problem is going to be fixed by a faster drive? Should I be looking for alternatives?

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  • Teaching logical/analytical thinking

    - by Joshua
    I have been trial running a club in which I teach programming for the past year and while they have progressed what they really lack is the most fundamental concept to programming, analytical thinking. As I now approach the second year of teaching to the children (aged 12 - 14) I am now realising that before I begin teaching them the syntax and how to actually program an app (or what they would rather, a game) I need to introduce them to analytical thinking first. I have already found Scratch and similar things such as Light-Bot and will most certainly be using the, to teach them how to implement their logical thinking but what I really need are some tips or articles on how to teach analytical thinking itself to children aged 12 - 14. What I'm looking for are some ideas on how to teach the kind of thinking that these kids will need in order to get them into programming, whether that be analytical, logical or critical. How and what should I teach them relating to the way their minds need to be wired when programming solutions to problems?

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  • From physics to Java programmer?

    - by inovaovao
    I'm a physics phd with little actual programming experience. I've always liked programming and played around with Basic and Pascal (also VB and Delphi) as a teen, but the largest actual project I completed was an assignement for the introductory computer science class in university where I wrote a nice little program (about 1500 lines of pascal) to display functions of 2 variables in 3D. I've had also a couple other projects of a few hundred lines range, but during my phd I didn't have (or take) the time to program more (string theory is hard guys!), beside playing around with ruby. Now I've decided that I'm more interested in programming than in physics and started to learn Java (hoping to pass the certification exam next week) and OO design. Still, I have trouble deciding on what to focus next (Java EE? Web development? algorithms and C programming?) in order to maximize my employement chances. Bear in mind that I'm aiming (mostly) at the swedish job market and that I'm 30 years old. So for the questions: Do you think that I have any chances to start and make a career in IT and programming coming from physics? What would be the best strategy to maximize my value in the field? Do you have suggestions as to where my physics background might be useful?

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  • Math questions at a programmer interview?

    - by anon
    So I went to an interview at Samsung here in Dallas, Texas. The way the recruiter described the job, he didn't make it sound like it was too math-oriented. The job basically involved graphics programming and C++. Yes, math is implied in graphics programming, especially shaders, but I still wasn't expecting this... The whole interview lasted about an hour and a half and they asked me nothing but math-related questions. They didn't ask me a single programming question, which I found odd. About all they did was ask me how to write certain math routines as a C++ function, but that's about it. What about programming philosophy questions? Design patterns? Code-correctness? Constness? Exception safety? Thread safety? There are a zillion topics that they could have covered. But they didn't. The main concern I have is that they didn't ask any programming questions. This basically implies to me that any programmer who is good at math can get a job here, but they might put out terrible code. Of course, I think I bombed the interview because I haven't used any sort of linear algebra in about a year and I forget math easily if I haven't used it in practice for a while. Are any of my other fellow programmers out there this way? I'm a game programmer too, so this seems especially odd. The more I learn, the more old knowledge that gets "popped" out of my "stack" (memory). My question is: Does this interview seem suspicious? Is this a typical interview that large corporations have? During the interview they told me that Google's interview process is similar. They have multiple, consecutive interviews where the math problems get more advanced.

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