Program Cannot Start Because MSVCR100.Dll Is Missing, What Can I Do?

The use of Biometrics is supported by Windows 10. Aside from that, it also supports PIN, password, picture password on all computers and if your computer has the proper hardware, Windows 10 also supports facial scanning, iris scanning, and even fingerprint scanning. You can see all these exciting features inside Settings > Accounts > Sign In Options. On the other hand, you can’t really expect to make use of all the above-mentioned features since it depends if the hardware is available to support them. One of the most interesting features is the use of Biometrics which is really useful in workplaces and so this post will show you how you can enable or disable the Domain Users Sign In on Windows 10 using Biometrics via Registry Editor or Group Policy Editor. But before you go on, you need to create a System Restore Point first since the modifications you’re about to do might affect the functioning of your computer. So in case something went wrong, you can always undo the changes you’ve made.

Option 1 – via Registry Editor

• Tap the Win + R keys to open the Run dialog box.
• Next, type “Regedit” in the field and hit Enter to open the Registry Editor.
• After that, navigate to the following registry path:

HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftBiometricsCredential Provider

• From there, right-click on the right-side panel and click on New > DWORD (32-bit) Value.
• And then set the name of the newly created DWORD as “Domain Accounts”.
• Afterward, click on “Domain Accounts” and set its value to “1”. This will allow the domain users to sign in to Windows 10 using Biometrics. While the value of 0 will disable the domain users sign in to Windows 10 using Biometrics.
• Exit the Registry Editor and restart your computer for the changes to take effect.

Option 2 – via Group Policy Editor

• Tap the Win + R keys to open the Run dialog box.
• Next, type “gpedit.msc” in the field and hit Enter to open the Group Policy Editor.
• After that, navigate to the following setting:

Computer Configuration > Administrative Templates > Windows Components > Biometrics

• Then double click on the following entries located on the right-side panel and set the radio button to Enabled on all of them.
  • Allow the use of Biometrics.
  • Allow users to log on using Biometrics.
  • Allow domain users to log on using biometrics.
• Now exit the Group Policy Editor and restart your computer to apply the changes made properly.

One of the essential parts of the Windows 10 operating system is the Microsoft Store as it is the distribution hub of numerous applications such as Netflix, Facebook, and many more. In fact, Microsoft is planning to make it a hub not just for UWP applications but also Windows Classic applications. Microsoft has already built a bridge with the power of Project Centennial which allows developers to migrate and upload their Windows Classic applications to the Microsoft Store. Although the Microsoft Store has been constantly improving, there are still times when you might face an error while using it. One of these errors is error 0x80131500. When you encounter this error, you will get the following error message on your screen:

“Try that again, Something happened at our end, Waiting a bit might help, The error code is 0x80131500 in case you need it.”

To fix this error, you can try changing your internet connection, toggle the date & time settings, change DNS, create a new user account, run the Microsoft Store Apps troubleshooter or reset the Microsoft Store as well re-register it using Windows PowerShell.

Option 1 – Try changing your internet connection

The first thing you can do is to change your internet connection. If you are using Ethernet, you can try to connect to a Wi-Fi connection instead and see if it helps.

Option 2 – Try to toggle the Date and Time settings

The first thing you can try is to sync the Date and Time of your computer as the wrong Date and Time settings are one of the most common causes of connection problems like the error 0x80131500. This is because of the incompatibility between the SSL Certificate validation date and the System Clock. Thus, you have to sync your System Clock. Refer to the steps below to do so.

• Start by tapping the Win + I keys to open the Windows Settings.
• Next, go to Time & Language > Date & time.
• From there, turn the toggle on for the “Set time automatically and Set time zone automatically” option on the right-side panel.
• After that, click on Region & language located on the left side panel and make sure that the Country or region on the right-side panel is set to the country you live in.
• Now close the Settings app and restart your computer and see if it fixes the problem or not.

Option 3 – Try to change the DNS Server

In this option, you can try changing your current DNS settings to the Google Public DNS as it could also help in fixing error 0x80131500. To do so, follow the steps below.

• The first thing you have to do is right-click on the network icon in the Taskbar and select Network and Sharing Center.
• Next, click on the “Change Adapter Settings” option.
• After that, search for the network connection that you are using to connect to the internet. Note that the option might be “Wireless Connection” or “Local Area Connection”.
• Right-click on your network connection and click on Properties.
• Then select the new window to choose the “Internet Protocol 4 (TCP/IPv4)” option.
• After that, click on the Properties button and click the checkbox in the new window for the option “Use the following DNS server addresses”.
• Type in “8.8.8.8” and “8.8.4.4” and click OK and exit.

Option 4 – Try to create a new Administrator User account

If you have a standard account, you can try creating a new account but this time, you create an administrator user account and then see if the error is fixed or not. Note that you have to sign in with your main account before you can create an admin account.

Option 5 – Run the Microsoft Store Apps troubleshooter

The Microsoft Store Apps Troubleshooter will help you in fixing the error 0x80131500. This is a great built-in tool from Microsoft that helps users fix any app installation issues. So this is worth a try to solve the problem. This built-in tool also helps you fix the Windows 10 Store if it isn’t working. To use the Windows Store Troubleshooter, follow the steps below.

1. Tap Win + I keys again to open the Windows Settings panel.
2. Go to Update & Security and then go to Troubleshoot.
3. On your right-hand side, scroll down to find the Windows Store Apps and then click on the Run the troubleshooter option and see if it fixes the problem.

Option 6 – Try to reset the Microsoft Store cache

Just like browsers, Microsoft Store also caches as you view apps and games so it is most likely that the cache is no longer valid and must be removed. To do so, follow the steps below.

• Right-click on the start button and click on Command Prompt (administrator).
• Next, type in the command, “exe” and tap Enter. Once you do, the command will clear the cache for the Windows Store app.
• Now restart your PC and afterward, try opening Microsoft Store again and then try to install your app or update your computer again.

Option 7 – Try to re-register the Microsoft Store app via PowerShell

• Tap the Win + X key combination or right-click on the Start button and click on the Windows PowerShell (Admin) option.
• If a User Account Control or UAC prompt appears, just click on Yes to proceed and open the Windows PowerShell window.
• Next, type in or copy-paste the following command to re-register the Microsoft Store app and tap Enter:

powershell -ExecutionPolicy Unrestricted Add-AppxPackage -DisableDevelopmentMode -Register $Env:SystemRootWinStoreAppxManifest.xml

• Wait for the process to be completed and then restart your computer.

Spring is almost here and with spring comes work, nature wakes up, people wake up, no more heating bills, time to start working, and time to start cleaning your PC. Good day everyone and welcome to another tip & trick for your PC. This time we are talking about cleaning your PC and keeping it up to software tight so you are ready for the upcoming spring season. Thank you for being with us and let's start:

Uninstall applications that you are not using

The unused applications can cause many issues for PC, from taking unnecessary disk space to even causing slower boot times if they have active services that require to be all-time up and running. They could slow down other applications like file explorer if they have extensions installed into them and can take RAM space with their background processes. If you are not using a particular application anymore or do not plan to use it soon it is always best practice to delete it from the system and thus removing all services and processes that go with it freeing so much-needed RAM and disc space.

Remove browser extensions you do not need

Browser extensions like applications can cause some issues with PC performance. if you spend a lot of time on the internet browser extensions can slow down browser and page loadings, they can make browsers take up more RAM memory and if they are outdated they could even present a serious security threat. Best practices are to keep only the extensions that you need all time, maybe some password managers or similar, extensions that you use on a daily basis, the rest should be uninstalled.

Remove things from the startup

Many services are booted along with Windows itself, some of them are crucial to the system even working, some not so. By eliminating not-needed services from the startup menu you will make sure that your boot times and overall performance of the system are in healthy form and that your PC is more responsive.

Organize files, folders, and desktop

The speeding of computer is not the only thing that you need to take care of, in order to be prepared and have maximum efficiency you will need to organize your files and folders as well. In a working environment, we often tend to save and place files all over the place, and in time they clog up desktop and hard drives. If the files are not well organized we will lose precious time trying to find anything that we need and require, so instead of wasting your time in locating files, why not organize them for easy and logical search so you can access them easily when needed.

Clean taskbar and start menu

Taskbar and start menu as well can be clogged with icons and non-organized application shortcuts and document shortcuts. Remove everything you do not need for that tidy and easily accessible access.

Sort bookmarks

It is very likely that you have plenty of bookmarks saved in our browser. It is also very likely that these bookmarks are not sorted and organized and now would be a great time to do it. Like files bookmarks also can cause you a lot of time loss if you need to find a specific one in a sea of many.

Run disc cleanup

Built-in disc cleanup utility will find temporary files, unused ones, and plenty of other junk on your hard drive. Now would be a great time to run it and get rid of junk files from your system.

Physically clean your computer

Now when we have taken care of the software part of our computer and system, it is time to clean up the computer itself. Unplug your computer and clean it, we will not go into details of this procedure, there is already an article on our site which deals with this part in detail so look it up if you need assistance with this part.

Clean your peripherals

Besides the computer for effective and pleasant work take care of your screen, keyboard, mouse, printer, etc. All of these devices need to be dust-free and clean if you expect them to behave on top of their game. If you would like to read more helpful articles and tips about various software and hardware visit errortools.com daily.

As you know, USB is now being widely used in all devices with USB A as the leading type with most devices based on it. Peripheral devices such as Pen Drives, External Hard disks, and many more also use a USB port. On the other hand, USB C is also coming up to be the next big standard in the computing world because of its high transfer speeds, wider compatibility as well as support for external Graphics Processing Units. However, just recently, USB 3.0 ports have been reported to cause the following error to pop up on Windows 10 computers every time a USB device is plugged in.

“Not enough USB controller resources. The controller does not have enough resources for this device.”

To fix this error, here are some guidelines you can check out. Make sure to follow them carefully.

Option 1 – Try to use a lower generation USB port

The first thing you can do is to try using a lower generation USB port as this issue mostly occurs when a device is connected to a USB 3,0 port. This means that you have to plug in your device to a USB 2.0 port and then see if it fixes the error or not. You can easily decipher a USB 3.0 port from a USB 2.0 port as the former is in blue.

Option 2 – Try to use a dock

You could also try to use a dock to resolve the error. Note that when too much power on laptops and notebooks are drawn from the USB ports and as a USB 3.0 port draws more power compared to a USB 2.0 port. Thus, if you plug in your USB storage device into a USB 2.0 port with the help of a dock, it should fix the problem.

Option 3 – Try disabling the xHCI Mode option in the BIOS

• First, boot your computer into the BIOS.
• Once your computer has booted, go to the Advanced tab.
• Next, make sure that the entry for “xHCI Pre-boot mode” is set to Disabled under the USB Configuration section.
• Now save the changes you’ve made and then restart your computer to Windows 10 and see if the error is now fixed.

Option 4 – Update or reinstall the Universal Serial Bus Controller driver

Since it could be a driver issue, you can try to update or reinstall the Universal Serial Bus Controller drivers using the Device Manager. Refer to the following steps:

• First, click the Start button and type “device manager”.
• Then click on the “Device Manager” from the search results to open it.
• From there, look for the “Universal Serial Bus controllers” option and then right click on each one of the USB drivers, especially the Generic USB Hub driver, and then select the Update Driver from the menu.
• Restart your PC and then click the “Search automatically for updated driver software” option.

Note: If updating the USB Controller drivers didn’t work, you can try to reinstall them instead.

Option 5 – Run the Hardware and Devices Troubleshooter

You could also run the Hardware and device Troubleshooter to try and fix the “Not enough USB controller resources” error.

• The first thing you need to do is click on Start and then on the gear-like icon to pull up the window for Settings.
• After opening Settings, look for the Update and Security option and select it.
• From there, go to the Troubleshoot option located on the left-hand side of the list.
• Next, select Hardware and Devices from the list and open the Troubleshooter and run it. Once it is doing its job, wait for it to complete the process and then restart the system.
• After the system restarts, check if the problem’s now fixed. If not, refer to the next option given below.

If you are visiting a single folder many times during the day it might be beneficial to place its shortcut on the desktop for easy access. But did you know that you can also set a keyboard shortcut for that same folder shortcut making it available simply by clicking desired key combination? In order to make a keyboard shortcut for the desired folder know that it is available only when you have a shortcut of the desired folder, it cannot be done on the folder itself, only on its shortcut. Now folder shortcut does not need to reside on desktop, you can place it anywhere you like, but it must be a shortcut. So the first step is of course to make a shortcut of the folder that you wish to have access via keyboard key combination and place it where you wish. Once you have done this step, right-click on it and choose properties. Inside properties at the top click on the Shortcut tab and then inside Shortcut Key, press the key combination that you wish to associate with this folder. Confirm with OK and start using fast folder access with your desired key combination.

Xpcom.dll Error Code - What is it?

To understand the Xpcom.dll error better, first, you need to know what Xpcom.dll file is. Xpcom.dll is basically a typical DLL (Dynamic Link Library) file. It is associated with Firefox developed by Mozilla Foundation for the Windows Operating System. DLL file contains small programs similar to exe (executable) files. Just like any other DLL file, Xpcom.dll helps loads and run programs smoothly. Xpcom.dll functions as a shared file that can be used to run multiple programs on your PC. Xpcom.dll error code occurs when Windows cannot properly load the xpcom.dll file. The error may pop up on the screen in any one of the following formats:

• "Xpcom.dll not found."
• "The file xpcom.dll is missing."
• "Cannot register xpcom.dll."
• "Cannot find C:\Windows\System32\xpcom.dll."
• "This application failed to start because xpcom.dll was not found. Re-installing the application may fix this problem."
• "Xpcom.dll Access Violation."
• "Cannot start Firefox. A required component is missing: xpcom.dll. Please install Firefox again."

The xpcom.dll error can occur during program installation or while rebooting your PC or when shutting it down.[/section]

Solution

Error Causes

It is difficult to narrow down a single cause of this error code simply because the Xpcom.dll error code may be triggered due to several reasons. Some of the common causes include:

• Invalid or corrupt xpcom.dll registry entry
• Viral infection
• Outdated PC drivers
• Another program overwrote the required version of xpcom.dll
• Xpcom.dll file is accidentally deleted or uninstalled
• Mozilla Foundation hardware failure

Further Information and Manual Repair

Here are the best, quick and easy DIY methods to resolve Xpcom.dll error code on your system within minutes:

Method 1: Update Window Drivers

To resolve the xpcom.dll error on your system, try updating Window drivers. To do this simply use the driver update wizard from within Device Manager. The driver update wizard walks you through the entire drive update process, making it easy and hassle-free for you to update drivers.

Method 2: Download and Install Xpcom.dll File

Since DLL are shared files and used to run and load multiple programs, it is possible that you might have accidentally removed this file while uninstalling a program on your system. This is the reason why the Xpcom.dll file goes missing. To retrieve the Xpcom.dll file simply go to the recycle bin. Reinstall the deleted program. However, if it still doesn’t resolve the error, then it is advisable to download and install the Xpcom.dll file from a trusted DLL file website over the internet.

Method 3: Scan for Viruses and Repair the Registry

If the error code occurs due to malware infection or is related to registry issues, then simply download Restoro. This is a user-friendly and multi-functional PC Fixer deployed with 6 scanners including a powerful antivirus and a registry cleaner. It is compatible with all Windows versions. Simply run it to remove all types of viruses infecting your system and clean/repair the registry. Click here to download Restoro and resolve the Xpcom.dll error on your PC.

If you open any program in your Windows 10 PC such as Outlook and suddenly get an error message saying, “Failed to register a VB Script dll. Reinstall or run Regsvr32.exe Vbscript.dll to self-register”, read on, as this post will guide you on what you can do to fix it. The obvious solution to this problem is by re-registering the “vbscript.dll” file on your computer. Refer to the instructions given below to re-register the VB Script DLL file and to fix the error.

• Step 1: Open the Command Prompt as an administrator from the WinX Menu.
• Step 2: After opening Command Prompt, type in the following command and tap Enter on your keyboard.

regsvr32.exe vbscript.dll

• Step 3: Once you enter the command, it will re-register the VB Script DLL file using the Windows OS tool called Regsvr32 or regsvr32.exe. This tool is a command-line utility used to register and unregister OLE controls such as DLL and ActiveX (OCX) controls in the Windows environment. After the execution of the command, you should see the following pop-up on your screen which means the re-registering of the concerned DLL file has succeeded.

On the other hand, if re-registering the DLL file didn’t work, then you can try logging in using an administrator account and then register the DLL file again or you could also use the System File Checker to figure out what the problem really is and automatically fix it. System File Checker or SFC is a built-in command utility that helps in restoring corrupted files as well as missing files. It replaces bad and corrupted system files with good system files. To run the SFC command, follow the steps given below.

• Tap Win + R to launch Run.
• Type in cmd in the field and tap Enter.
• After opening Command Prompt, type in sfc /scannow

The command will start a system scan which will take a few whiles before it finishes. Once it’s done, you could get the following results:

1. Windows Resource Protection did not find any integrity violations.
2. Windows Resource Protection found corrupt files and successfully repaired them.
3. Windows Resource Protection found corrupt files but was unable to fix some of them.

Hello everyone, last time we were talking about disk cleanup and its benefits, but as you need to keep your System clean you should also clean and keep your hardware clean as well. Many system issues could be traced and could happen due to dirty PC. In this article, we will give you tips on how to perform safely cleaning on your computer and hopefully point good sides to it so you can develop a healthy habit of regularly cleaning it and keeping it tidy. Keeping your PC clean is not rocket science and you can do it with things you already and probably have in your house. One thing that I would recommend tho to purchase is antistatic gloves since they could prevent any kind of electrostatic discharges thus protecting your electric components. If you have the option to disconnect your PC and get it outdoors, I would highly recommend this approach since all the dust will be dusted outside and not in the room where your computer is. If you can not it is still ok, but since some portion of dust will be set in the room, you might need to dust your room after cleaning your computer.

Cleaning outside case & redusting inside

The first thing after disconnecting your computer is to dust it from outside, here you will need a vacuum cleaner and a brush, gently brush outside dust from your casing and vacuum it with your vacuum cleaner. You can use dustcloth for larger parts but use the brush for fans and connectors. After you have done cleaning the outside part, open the side of your computer casing, put on your antistatic gloves, and get a fine and soft brush, repeat dusting and vacuuming of the inner parts of your computer. If your computer is not regularly been cleaned this part will take a little longer since there would be excess dust inside and it will take a longer time to vacuum it all but keep going until you are left with no dirt.

Cleaning it inside

Fans are troublesome to clean since they will rotate when brushed and that could make you miss certain sports, in order to battle this get a tape and stick the fan into one position, brush areas that you can reach, then unstick it, rotate the head, stick it again in another position and dust off remaining areas which you could not reach before. If your computer is very dirty and some hard dirt is at bottom of the connectors, disconnect desired component and clean the connection properly. plug it back in immediately after cleaning to avoid connecting it somewhere else. Harder stains that could not be dusted could be cleaned with little alcohol. Get your dustcloth just a little wet with alcohol, just a corner, and gently wipe out sticky dust or spills if they are present. Leave it 10 minutes for alcohol to evaporate before plugging it back into an electric socket.

Thermal paste and cable management

If you have money and expertise, every 2 years would be a good idea to change the thermal paste on your processor, all you need to do is buy it from your local computer store online, remove the CPU fan clean the CPU and bottom of the fan and apply new thermal paste, place fan back and lock it. If you do not have expertise in this area, call someone who has to show you how it is done. When cleaning it would be a good idea if you do not have any cable management to do it now, nice and tidy cables not only look good, they also improve your air circulation inside your casing making your computer cooling better. once you are done with it, close back the casing side and plug it back in the wall.

Peripherals

When you are cleaning your computer, do yourself a favor and clean your keyboard, mouse, and screen as well. the keyboard can be quickly cleaned with compressed air in the can and screen and mouse with dustcloth. That's it, remember, keep your PC clean and tidy and enjoy the benefits of non-hardware malfunctions caused by dirt and dust.

If you have encountered the “Windows Cannot Find a System Image on This Computer” error while you are trying to restore a system image, then read on as this post will guide you in resolving this problem. A system image is basically a backup of your whole data in the system. For instance, it can be the backup data of your hard disk or the whole hard disk itself, or one of the volumes. This is really useful in some cases like when you are not able to get back into your system for some reason or when your system has been corrupted. In such cases, you can utilize this feature and get going safe and sound. However, not all things go the way as expected like when you make a system image of a drive for instance, or use that backup to restore data and you suddenly encounter the “Windows Cannot Find a System Image on This Computer” error. This kind of error occurs due to a number of reasons but worry not for your data is safe and you can fix this error easily. This error is most likely triggered by changing the name of the “WindowsImageBackup” folder. Renaming this folder will certainly be an issue since it is the one that stores all your data. Aside from renaming the WindowsImageBackup folder, renaming the sub-folders can also cause this error which means that renaming the sub-folders of the WindowsImageBackup folder can trigger the error. To fix this error, here are some suggestions that might help:

Option 1 – Try putting the WindowsImageBackup folder in the Root directory

Windows will have issues finding the WindowsImageBackup folder if it isn’t in the root directory of the drive so if it is not there, the “Windows Cannot Find a System Image on This Computer” error will pop up. When a folder is in a root directory, it means that it shouldn’t be stored within a folder but in the main directory instead.  Thus, you need to put the WindowsImageBackup folder in the root directory to fix the error.

Option 2 – Don’t add any sub-folders in the WindowsImageBackup folder

Another cause of the error is when you add sub-folders in the WindowsImage Backup folder. Adding any sub-folders in this folder will only trigger the error so you should leave the folder as it is and you must not make any modifications to it. So if you have added sub-folders in it, make sure to remove them right away.

Option 3 – Make sure that there is one system image per USB drive

The error can also appear if you’ve stored multiple images inside a single USB drive as it could confuse Windows and will trigger the “Windows Cannot Find a System Image on This Computer” error. Note that storing system images of different volumes of your hard disk in a single USB will prevent you from restoring your data.

Option 4 – Try renaming the System Image folder

If you’ve just changed the name of the System Image folder after you store it on a USB stick or other external device, then it’s no wonder why you’re getting the “Windows Cannot Find a System Image on This Computer” error. Windows search for the default name, “WindowsImage Backup” folder when restoring your data so if it is not able to find it, it throws up this error instead. To fix the error, you need to change the folder back to its default name which is “WindowsImageBackup”.

Option 5 – Check the WindowsImageBackup sub-folders

As mentioned earlier, renaming sub-folders in the WindowsImageBackup folder can trigger the error so if you have renamed sub-folders in this folder, you need to change them back to their default names so that you can restore your data peacefully.

Error 0X800F080C is tied to corrupted system files and .NET framework issues. In this article, we will focus on how to fix it starting first with .NET fixes and then moving to system-related ones. Follow the guide step by step so you can fix this error fast and easily.

.NET issues

As previously stated 0X800F080C error can occur due to issues with .NET framework, 3.5 framework to be more precise and there are two ways we can fix this error. Follow the guide below as presented:

1. Install .NET 3.5 framework from Windows features

   First thing is to try and install the framework from Window features itself. Sometimes installation and activation of .NET 3.5 in other ways can result in this error. To install it do the following: Press ⊞ WINDOWS + R to open the run dialog Inside run type in appwiz.cpl and press ENTER to open up the Programs and Features menu Inside the Programs and Features menu click on Turn Windows features on or off. Check the box associated with .NET Framework 3.5 (this package includes .NET 2.0 and 3.0) Press OK Click on YES and wait for the package to be installed then reboot your PC

2. Run the .NET Repair Tool

   If the previous step was not successful or you already had .NET 3.5 installed then run the troubleshooter in order to fix issues. Go to the official Microsoft .NET framework repair tool website here and download it. Once downloaded install the tool and follow onscreen instructions.

Corrupted system files

If the previous solution has not provided you with results then you have system file corruption that needs to be fixed. Move from one solution to another as presented below:

1. Run SFC scan

   SFC scan is a built-in Windows tool for solving corrupted system files issues, it is fully automated and does not require from the user any kind of knowledge or information. To run it and scan the system do the following: Press ⊞ WINDOWS + X to open the secret menu Left-click on the command prompt (admin) In command prompt type SFC /SCANNOW and press ENTER Wait for the process to finish, do not interrupt it and once it is done, restart your computer

2. Run DISM scan

   DISM scan is similar to SFC scan but it tackles different types of system file corruption and it is recommended to run it also after SFC has been completed. Please note that for DISM scan to be successful you will need a stable internet connection since DISM will replace corrupted files with new ones downloaded from Microsoft. To run it do the following: Press ⊞ WINDOWS + X to open the secret menu Left-click on the command prompt (admin) inside command prompt type: exe /online /cleanup-image /scanhealth followed by ENTER, then type: Dism.exe /online /cleanup-image /restorehealth also followed with ENTER. Leave scan to finish and reboot your PC