Regex ignore case sensitivity

Question

How can I make the following regex ignore case sensitivity  It should match all the correct characters but ignore whether they are lower or uppercase   G a-b

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regular expression for validate  abc  ignoring case sensitive     i  abc

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Just for the sake of completeness I wanted to add the solution for regular expressions in C   with Unicode   std  tr1  wregex pattern szPattern  std  tr1  regex constants  icase    if  std  tr1  regex match szString  pattern

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Assuming you want the whole regex to ignore case  you should look for the i flag  Nearly all regex engines support it    G a-b    i  string match  G a-b       i     Check the documentation for your language platform tool to find how the matching modes are specified   If you want only part of the regex to be case insensitive  as my original answer presumed   then you have two options    Use the   i  and  optionally    -i  mode modifiers     i G a-b   -i     Put all the variations  i e  lowercase and uppercase  in the regex - useful if mode modifiers are not supported    gG  a-bA-B       One last note  if you re dealing with Unicode characters besides ASCII  check whether or not your regex engine properly supports them

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JavaScript If you want to make it case insensitive just add i at the end of regex   Test  match   A-Z  gi    Returns   quot T quot    quot e quot    quot s quot    quot t quot   Without i  Test  match   A-Z  g    Returns   quot T quot

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C   using System Text RegularExpressions          Regex Match      input   Check This String       pattern   Regex Pattern       options  RegexOptions IgnoreCase    specifically  options  RegexOptions IgnoreCase

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Addition to the already-accepted answers   Grep usage   Note that for greping it is simply the addition of the -i modifier  Ex  grep -rni regular expression to search for this  regular expression   r ecursively  case  i nsensitive  showing line  n umbers in the result   Also  here s a great tool for verifying regular expressions  https   regex101 com   Ex  See the expression and Explanation in this image     References    man pages  man grep   http   droptips com using-grep-and-ignoring-case-case-insensitive-grep

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As I discovered from this similar post  ignorecase in AWK   on old versions of awk  such as on vanilla Mac OS X   you may need to use  tolower  0     pattern      IGNORECASE or   i  or  pattern i will either generate an error or return true for every line

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You can practice Regex In Visual Studio and Visual Studio Code using find replace   You need to select both Match Case and Regular Expressions for regex expressions with case  Else  A-Z  won t work enter image description here

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In JavaScript you should pass the i flag to the RegExp constructor as stated in MDN  const regex   new RegExp   abc     i     regex test  ABc       true

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You also can lead your initial string  which you are going to check for pattern matching  to lower case  And using in your pattern lower case symbols respectively

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Depends on implementation but I would use    i G a-b     VARIATIONS      i  case-insensitive mode ON       -i  case-insensitive mode OFF   Modern regex flavors allow you to apply modifiers to only part of the regular expression  If you insert the modifier   im  in the middle of the regex then the modifier only applies to the part of the regex to the right of the modifier  With these flavors  you can turn off modes by preceding them with a minus sign   -i     Description is from the page  https   www regular-expressions info modifiers html

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The i flag is normally used for case insensitivity  You don t give a language here  but it ll probably be something like  G ab    i or    i G ab

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In Java  Regex constructor has   Regex String pattern  RegexOption option    So to ignore cases  use  option   RegexOption IGNORE CASE

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gG  aAbB    probably simples solution if the pattern is not too complicated or long

[regex] Regex: ignore case sensitivity

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