Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

r"
"
g

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(\\d[\\w\\W]*?(?=(?:\\d\\d*\\. )|$))"; final String string = "1. A DDR4 DIMM with a PC rating of PC4-17000 is running at what speed?\n" + "a. 1800 MHz\n" + "b. 2000 MHz\n" + "c. 2133 MHz\n" + "d. 3000 MHz\n" + "2. What can a DIMM use to hold data and amplify a signal just before the data is written to the module?\n" + "a. EDO\n" + "b. registers\n" + "c. parity\n" + "d. CAS\n" + "3. A DDR4 DIMM running at a speed of 2666 MHz has what PC rating?\n" + "a. PC4-17000\n" + "b. PC4-24000\n" + "c. PC4-21300\n" + "d. PC4-30000\n" + "4. DIMMs used in servers can provide additional reliability if they use what specific technology?\n" + "a. EDO\n" + "b. dual ranked\n" + "c. ECC\n" + "d. PC3\n" + "5. Which statement is true regarding DIMM technologies?\n" + "a. DDR2 uses 184 pins\n" + "b. DDR3 is backward compatible with DDR2\n" + "c. SDRAM runs synchronized with the system clock\n" + "d. the S in SDRAM stands for static\n" + "6. What is the transfer rate of a 64-bit module running at 1600 MHz?\n" + "a. 1600 MB/second\n" + "b. 3200 MB/second\n" + "c. 6400 MB/second\n" + "d. 12800 MB/second\n" + "7. What should you install in a server room that will save space by allowing you to control multiple servers with\n" + "a single mouse, keyboard, and monitor?\n" + "a. a MIDI connector\n" + "b. a digitizer\n\n" + "c. biometric device\n" + "d. a KVM switch\n" + "8. What is the current maximum storage capacity limit of a magnetic tape?\n" + "a. 500GB\n" + "b. 15TB\n" + "c. 185TB\n" + "d. 300TB\n" + "9. A DAT72 tape is also known by what term?\n" + "a. DDS-2\n" + "b. DDS-3\n" + "c. DDS-4\n" + "d. DDS-5\n" + "10. Three long beeps during the POST sequence on an Intel BIOS are an indication of what type of issue?\n" + "a. motherboard problem\n" + "b. memory error\n" + "c. system overheat\n" + "d. keyboard controller problem\n" + "11. What does a single beep or no beep imply during the startup of a computer?\n" + "a. a video problem\n" + "b. a memory error\n" + "c. all POST tests passed\n" + "d. a keyboard controller problem\n" + "12. If you see an error message that reads \"Processor thermal trip error\", what is the likely problem?\n" + "a. the power supply is inadequate\n" + "b. the processor has overheated\n" + "c. the processor has failed\n" + "d. a memory module might be bad\n" + "13. If the startup BIOS can't find a device to use to load the operating system, what error message is likely to\n" + "appear?\n" + "a. Fixed disk error\n" + "b. Blue screen of death\n" + "c. Error in ntoskernel\n" + "d. Error loading Windows\n" + "14. What type of backlighting receives DC power directly from a motherboard and doesn't use an inverter?\n" + "a. CCFL\n\n" + "b. LED\n" + "c. Plasma\n" + "d. OLED\n" + "15. What type of backlighting is also called fluorescent backlighting, and was first used in laptop monitors?\n" + "a. LED\n" + "b. liquid crystal display\n" + "c. plasma monitor\n" + "d. CCFL\n" + "16. What is the distance between adjacent dots on a screen known as?\n" + "a. viewing angle\n" + "b. refresh rate\n" + "c. native resolution\n" + "d. pixel pitch\n" + "17. What component of a processor handles all logical comparisons and calculations inside the processor?\n" + "a. ALU\n" + "b. register\n" + "c. bus\n" + "d. control unit\n" + "18. A processor housing that contains more than one processor is referred to as what term?\n" + "a. multithreaded processor\n" + "b. multicore processor\n" + "c. multiprocessing processor\n" + "d. multihoused processor\n" + "19. Hybrid processors that can process 32 bits or 64 bits are known by what term?\n" + "a. x86 processors\n" + "b. Itanium processors\n" + "c. Dual Mode processors\n" + "d. x86-64 processors\n" + "20. What component of a processor holds instructions waiting to be processed by the ALU?\n" + "a. register\n" + "b. bus\n" + "c. internal memory cache\n" + "d. control unit\n" + "21. What is a typical symptom of a CMOS battery failure?\n" + "a. POST code beeps\n\n" + "b. time and date settings lost\n" + "c. continuous reboots\n" + "d. blue screen of death\n" + "22. When a static image stays on a monitor for many hours leaving a permanent impression of that image on the\n" + "monitor, what term is used to describe the condition?\n" + "a. image cling\n" + "b. burn-in\n" + "c. screen blanking\n" + "d. screen freezing\n" + "23. When might an LCD monitor experience distorted geometry?\n" + "a. only when the wrong video cable is used\n" + "b. if the pixel pitch is not high enough\n" + "c. if the screen is overheating\n" + "d. the screen is not set to native resolution\n" + "24. What term refers to horizontally torn images on a screen, which occur when the video feed from the video\n" + "controller gets out of sync with the refresh rate of the monitor?\n" + "a. burn-in\n" + "b. left-ins\n" + "c. rips\n" + "d. artifacts\n" + "25. What might be the cause of a black screen right after you install a new video card?\n" + "a. no video card is detected\n" + "b. the onboard video is not disabled in BIOS\n" + "c. you installed the video card in the wrong slot\n" + "d. the video card has insufficient RAM\n" + "26. What technology is used to assure that the logical block addressing on a solid state drive does not always\n" + "address the same physical blocks, in order to distribute write operations?\n" + "a. wear leveling\n" + "b. bit shifting\n" + "c. block sliding\n" + "d. data migration\n" + "27. Which statement regarding hard drives is incorrect?\n" + "a. the 3.5\" size is typically used in desktops\n" + "b. a solid state drive has no moving parts\n" + "c. solid state drives are less expensive than magnetic hard drives\n" + "d. tracks on a hard drive are divided into sectors\n\n" + "28. Which statement regarding the selection of a hard drive is accurate?\n" + "a. a faster spindle speed keeps the drive cooler but doesn't improve performance\n" + "b. PATA drives are backward compatible with SATA drives\n" + "c. USB drives are a good choice for fast internal drives\n" + "d. magnetic drives have larger capacity for the money than solid state drives\n" + "29. What hard drive technology is used to predict when a drive is likely to fail?\n" + "a. S.S.D.\n" + "b. S.M.A.R.T.\n" + "c. N.A.N.D.\n" + "d. E.E.P.R.O.M.\n" + "30. The hard drive firmware, UEFI/BIOS, and the OS address the sectors on a hard drive utilizing what\n" + "technology?\n" + "a. logical sector addressing\n" + "b. low level formatting\n" + "c. logical block addressing\n" + "d. high level formatting\n" + "31. What process writes sector markings to a hard drive?\n" + "a. partitioning\n" + "b. low-level formatting\n" + "c. high-level formatting\n" + "d. sector provisioning\n" + "32. Which rotation speed is not a typical spindle rotation speed for magnetic hard drives?\n" + "a. 3100\n" + "b. 5400\n" + "c. 7200\n" + "d. 10000\n" + "33. What type of processor memory is located on the processor chip (processor die)?\n" + "a. Level 0 cache\n" + "b. Level 1 cache\n" + "c. Level 2 cache\n" + "d. Level 3 cache\n" + "34. What type of RAM is typically installed onto a motherboard and loses data rapidly, requiring it to be\n" + "refreshed often?\n" + "a. SRAM\n" + "b. CMOS RAM\n\n" + "c. DRAM\n" + "d. Flash RAM\n" + "35. Where can the Execute Disable Bit (EDB) technology be disabled?\n" + "a. In the EDB configuration software.\n" + "b. In the BIOS / UEFI setup screen\n" + "c. In the Windows Device Driver screen\n" + "d. In the Windows command line EDB utility\n" + "36. What is the general name of the processor feature that AMD calls HyperTransport?\n" + "a. multicore processing\n" + "b. multithreading\n" + "c. virtualization support\n" + "d. integrated graphics\n" + "37. Involving both software and hardware, what technology is meant to protect digital content and prevent\n" + "piracy?\n" + "a. HDMI\n" + "b. DRM\n" + "c. PPM\n" + "d. DVI\n" + "38. Which type of video port provides a digital-only signal?\n" + "a. DVI-I\n" + "b. DVI-D\n" + "c. DVI-A\n" + "d. VGA\n" + "39. What should you do if the system continually reboots and you can't read the error message produced on a\n" + "blue screen?\n" + "a. press F8 as Windows starts up\n" + "b. press Pause so you can see the screen output\n" + "c. press Ctrl+Print Screen to print the screen output\n" + "d. press Esc as soon as you see the blue screen\n" + "40. One long and two short beeps when using an Award BIOS is an indication of what issue?\n" + "a. memory error\n" + "b. hard drive not found\n" + "c. a video problem\n" + "d. a CPU problem\n" + "41. What is an auto-switching AC adapter?\n\n" + "a. an adapter that can switch between line power and battery power\n" + "b. an adapter that switches between two PCs\n" + "c. an adapter that can use 110V or 220V AC power\n" + "d. an adapter that can switch between AC or DC\n" + "42. A missing standoff could create what potential problem?\n" + "a. a short on the motherboard\n" + "b. the computer boots, but can't connect to the network\n" + "c. data is deleted from the hard drive\n" + "d. you see lines on the video monitor\n" + "43. What is an indication that an inadequate power supply is the source of an intermittent problem?\n" + "a. the power supply whines when you first turn on the system\n" + "b. you don't see any indicator lights or fans spinning\n" + "c. BIOS loses its date and time settings\n" + "d. the system tries to boot from the wrong device\n" + "44. Which of the following protects your computer from brownouts or sags?\n" + "a. degaussing\n" + "b. GPU\n" + "c. surge protector\n" + "d. UPS\n" + "45. When populating a motherboard with DIMM modules, what configuration option will not work?\n" + "a. using two different manufacturer's memory\n" + "b. mixing memory speeds\n" + "c. leaving a slot unpopulated\n" + "d. mixing unbuffered with registered\n" + "46. What component of a motherboard is not considered to be a field replaceable unit?\n" + "a. processor\n" + "b. RAM\n" + "c. CMOS battery\n" + "d. chipset\n" + "47. Why might you disable quick booting features in BIOS when you are troubleshooting a problem?\n" + "a. to enable access the advanced boot menu\n" + "b. quick booting prevents Windows from logging errors\n" + "c. to see a full POST report\n" + "d. quick booting bypasses the POST\n" + "48. Which statement regarding the USB standard and USB devices is accurate?\n\n" + "a. up to 64 USB devices can be daisy chained together\n" + "b. USB uses parallel data transmissions\n" + "c. a USB cable has four wires, two for power and two for communication\n" + "d. USB devices must supply their own power\n" + "49. A SuperSpeed USB port is capable of attaining what maximum data transfer speed?\n" + "a. 1.2 Gbps\n" + "b. 1.5 Gbps\n" + "c. 5 Gbps\n" + "d. 6 Gbps\n" + "50. Which statement regarding the Firewire standard is accurate?\n" + "a. data is transferred on a parallel bus\n" + "b. 1394b allows up to 16 daisy-chained devices\n" + "c. FireWire 800 uses a 4-pin connector\n" + "d. FireWire devices are hot-swappable\n" + "51. If you are trying move a hard drive from a non-working computer to a working computer for the purposes of\n" + "accessing the data on the drive, what must you have?\n" + "a. you must install the drive in a drive bay\n" + "b. you must manually assign a drive letter\n" + "c. you must have an Administrator password before you can access the data on the drive\n" + "d. the drive must be initialized before you can access it\n" + "52. What technology in a DIMM informs the BIOS of the module's size, speed, voltage, and data path width?\n" + "a. SPD\n" + "b. ECC\n" + "c. Buffers\n" + "d. DDR\n" + "53. If a computer is performing slowly due to file fragmentation, what Windows tool can be utilized to rearrange\n" + "fragments?\n" + "a. Computer Management\n" + "b. defragmentation tool\n" + "c. defraggler\n" + "d. Disk cleanup\n" + "54. Which of the following is NOT the name of a current family of Intel processors?\n" + "a. Duo\n" + "b. Core\n" + "c. Atom\n\n" + "d. Celeron\n" + "55. What Intel processor technology interconnects the processor, chipset, and wireless network adapter as a unit,\n" + "improving laptop performance?\n" + "a. Pentium\n" + "b. Core i5\n" + "c. Celeron\n" + "d. Centrino\n" + "56. What happens when a flash memory card is installed in a slot and it is recognized by Windows?\n" + "a. a window appears prompting you to initialize the device\n" + "b. a drive letter is assigned to the device and you can see it in Explorer\n" + "c. Windows automatically partitions and formats the device\n" + "d. the files are copied from the device to your Documents folder\n" + "57. A PCIe 6/8 pin connector for providing auxiliary power to PCIe cards utilizes what voltage?\n" + "a. +5v\n" + "b. -12V\n" + "c. +12v\n" + "d. +15v\n" + "58. What is the most used rail on a power supply?\n" + "a. +3.3V\n" + "b. -5V\n" + "c. -12V\n" + "d. +12V\n" + "59. Which of the following is NOT a solution to an overheating problem?\n" + "a. verify that cables are not obstructing airflow\n" + "b. remove the covers from empty expansion slots\n" + "c. be sure the case is not sitting on a carpet\n" + "d. remove dust from the power supply, vents, and cooler fans\n" + "60. If you suspect your system is overheating, how can you determine the CPU temperature?\n" + "a. in Windows, go to System Information\n" + "b. the CPU has a temperature display screen\n" + "c. press a room thermometer on the top of the CPU\n" + "d. go into UEFI/BIOS setup and find the temperature monitors for the system\n" + "61. What statement best describes a RAID 5?\n" + "a. data from one drive is mirrored to another\n" + "b. it improves performance but not fault tolerance\n\n" + "c. it requires 3 or more drives and uses parity checking\n" + "d. it takes at least four disks and data is striped and mirrored\n" + "62. Which type of RAID volume is used for fault tolerance and only requires two drives?\n" + "a. RAID0\n" + "b. RAID1\n" + "c. RAID5\n" + "d. RAID10\n" + "63. What type of RAID is a combination of mirroring and striping?\n" + "a. RAID0\n" + "b. RAID1\n" + "c. RAID5\n" + "d. RAID10\n" + "64. Why might you want to use a RAID 0 disk configuration?\n" + "a. to improve overall disk performance\n" + "b. RAID 0 drives are less expensive than other RAID drives\n" + "c. to prevent data loss in case of a drive failure\n" + "d. because RAID 0 provides an automatic disk backup\n" + "65. What Intel socket recommends the use of a liquid cooling system?\n" + "a. LGA1150\n" + "b. LGA1151\n" + "c. LGA1750\n" + "d. LGA2011\n" + "66. Which type of memory can support quad, triple, and dual channels?\n" + "a. DDR3\n" + "b. DDR2\n" + "c. DDR\n" + "d. RIMM\n" + "67. If you are adding a hard drive to a system that already has a drive with Windows installed on it, what should\n" + "you do?\n" + "a. you should boot from the Windows setup DVD to prepare the new drive\n" + "b. boot Windows and use Disk Management to prepare the new drive\n" + "c. use the BIOS setup screen to partition and format the new drive\n" + "d. check that the new hard drive must use the same standard as the Windows drive\n" + "68. What command line utility can be used to repair the BCD on a Windows installation?\n" + "a. chkdsk\n\n" + "b. fsutil\n" + "c. dfrgl\n" + "d. bootrec\n" + "69. The SATA/600 standard is also known by what other name?\n" + "a. SATAI\n" + "b. SATAII\n" + "c. SATAIII\n" + "d. SATA revision 4\n" + "70. What SATA standard provides a transfer rate of 3 Gb/sec?\n" + "a. SATA1\n" + "b. SATA2\n" + "c. SATA3\n" + "d. SATA4\n" + "71. A SATA data cable has how many pins?\n" + "a. 4 pins\n" + "b. 7 pins\n" + "c. 10 pins\n" + "d. 15 pins\n" + "72. Which of the following is a requirement for supporting the Aero user interface?\n" + "a. at least 128 KB video memory\n" + "b. DirectX 9 or higher\n" + "c. an HDMI video port\n" + "d. Windows XP with SP3\n" + "73. In order to enable the Windows 7 Aero user interface, how much video memory must be available to the\n" + "video controller?\n" + "a. 64MB\n" + "b. 128MB\n" + "c. 256MB\n" + "d. 1GB\n" + "74. What icon might you see in Device Manager that indicates a problem with a device?\n" + "a. blue circle\n" + "b. yellow triangle\n" + "c. red square\n" + "d. white oval\n" + "75. What is a basic principle that applies to both internal and external devices?\n\n" + "a. when connecting a faster device to a slower port, the port adapts to the speed of the device\n" + "b. if you have multiple devices to install, it's best to install them at the same time\n" + "c. for most installations, install the device first, then the device driver\n" + "d. some devices don't require a software component for them to work properly\n" + "76. When installing a new device, which statement is accurate?\n" + "a. a mouse may not require an additional device driver installation\n" + "b. Vista drivers never work with Windows 7\n" + "c. 32-bit drivers can be installed in a 64-bit OS\n" + "d. 64-bit drivers can be installed in a 32-bit OS\n" + "77. How many layers of data can exist on a single side of a Blu-ray disc?\n" + "a. 1\n" + "b. 2\n" + "c. 3\n" + "d. 4\n" + "78. What is the most likely result of a correctly installed processor, but an incorrectly installed cooler?\n" + "a. powers on, but nothing else happens\n" + "b. boot process begins, but system suddenly turns off after a short period\n" + "c. system does not power on at all\n" + "d. BIOS setup does not recognize the processor correctly\n" + "79. When testing a laptop power connector, how close should the voltage measured be to the accepted voltage of\n" + "the laptop?\n" + "a. +/- 10%\n" + "b. +/- 5%\n" + "c. +/- 1%\n" + "d. The voltage should be exactly the same\n" + "80. If a user on a laptop complains that they are unable to sign into Windows even though they are certain they\n" + "are entering the correct password, what should you have them do?\n" + "a. perform a reboot\n" + "b. bring the laptop to an authorized repair shop\n" + "c. check the NumLock indicator on the laptop\n" + "d. Replace the laptop keyboard\n"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html