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How to do case insensitive search in Vim

Asked 2023-09-20 21:00:26 View 762,092

I'd like to search for an upper case word, for example COPYRIGHT in a file. I tried performing a search like:

/copyright/i    # Doesn't work

but it doesn't work. I know that in Perl, if I give the i flag into a regex it will turn the regex into a case-insensitive regex. It seems that Vim has its own way to indicate a case-insensitive regex.

Answers

You can use the \c escape sequence anywhere in the pattern. For example:

/\ccopyright or /copyright\c or even /copyri\cght

To do the inverse (case sensitive matching), use \C (capital C) instead.

Answered   2023-09-20 21:00:26

  • Also, \c can appear anywhere in the pattern, so if you type a pattern and then decide you wanted a case-insensitive search, just add a \c at the end. - anyone
  • I like to add set ignorecase for case-insensitive searching in my vimrc, and I can use \C to do a case-sensitive search similar to what @AlokSinghal mentioned. - anyone
  • There's also set smartcase which will automatically switch to a case-sensitive search if you use any capital letters. - anyone
  • Just want to add to Zaz's comment. set smartcase applies only when set ignorecase is already active. I was stumped on this for a while. See Vim Tips. - anyone
  • @coderMe, It's the capitalization, \c versus \C - anyone

As well as the suggestions for \c and ignorecase, I find the smartcase very useful. If you search for something containing uppercase characters, it will do a case sensitive search; if you search for something purely lowercase, it will do a case insensitive search. You can use \c and \C to override this:

:set ignorecase
:set smartcase
/copyright      " Case insensitive
/Copyright      " Case sensitive
/copyright\C    " Case sensitive
/Copyright\c    " Case insensitive

See:

:help /\c
:help /\C
:help 'smartcase'

Answered   2023-09-20 21:00:26

  • The problem with ignorecase is that it affects substitutions as well as searches. I find that it makes sense to have (smart) case-insensitive searches but case-sensitive substitutions by default. But there's no way to do that that I know. - anyone
  • Worth noting that for smartcase to work, you also need set ignorecase. Great tip though, thanks! - anyone
  • I believe you could just use a \C in your search expression for substitutions, like this: :%s/lowercasesearch\C/replaceString/g. This doesn't create the default functionality you desire, but it does allow you to force case-sensitivity for replacements while still benefiting from smartcase when searching. - anyone
  • You can also set the I flag on a substitution to force the pattern to be case-sensitive. Like :%s/lowercasesearch/replaceString/gI. - anyone
  • Note from the help page (useful if you are "*" addicted like me): After "*" and "#" you can make 'smartcase' used by doing a "/" command, recalling the search pattern from history and hitting <Enter>. - anyone

You can set the ic option in Vim before the search:

:set ic

To go back to case-sensitive searches use:

:set noic

ic is shorthand for ignorecase

Answered   2023-09-20 21:00:26

  • also your only option if you're unlucky enough to still use Vi instead of Vim. \c doesn't work in vi. - anyone

You can issue the command

:set ignorecase

and after that your searches will be case-insensitive.

Answered   2023-09-20 21:00:26

You can use in your vimrc those commands:

  • set ignorecase - All your searches will be case insensitive
  • set smartcase - Your search will be case sensitive if it contains an uppercase letter

You need to set ignorecase if you want to use what smartcase provides.

I wrote recently an article about Vim search commands (both built in command and the best plugins to search efficiently).

Answered   2023-09-20 21:00:26

  • It seems that set smartcase does not perform case insensitive searches if I do not use uppercase letters...is that normal? - anyone
  • Ok, just read below that you have to both set ignorecase and smartcase to have it work. Sorry about that! - anyone

To switch between case sensitive and insensitive search I use this mapping in my .vimrc

nmap <F9> :set ignorecase! ignorecase?

Answered   2023-09-20 21:00:26

  • Yes, but ignorecase? shows you the current state of the flag. (in the command line) - anyone
  • Thank you! To me, this is the most useful answer on the page: a way to quickly toggle between the two modes depending on what you're searching for at that exact moment. - anyone
  • Yes, it's better to have ignorecase? so you know the current state. - anyone
  • BTW, it's better to add <Cr> at the end, so the command is validated, and you don't have to hit the enter key (at least with neovim). - anyone

The good old vim[grep] command..

:vimgrep /example\c/ &
  • \c for case insensitive
  • \C for case sensitive
  • % is to search in the current buffer

enter image description here

Answered   2023-09-20 21:00:26

By default, all searches in vi are case-sensitive. To do a case-insensitive search, go into command mode (press Escape), and type-
:set ignorecase
You can also type - :set ic as an abbreviation.

To change back to case-sensitive mode, type-
:set noignorecase or :set noic in command mode

Answered   2023-09-20 21:00:26

As others suggested:

:set ic

But the cool stuff is You can toggle such modes with:

:set ic!

Answered   2023-09-20 21:00:26

I prefer to use \c at the end of the search string:

/copyright\c

Answered   2023-09-20 21:00:26

put this command in your vimrc file

set ic

always do case insensitive search

Answered   2023-09-20 21:00:26

  • I don't know why but my vim is set to case-insensitive by default, to counter this. use set noic. - anyone

As @huyz mention sometimes desired behavior is using case-insensitive searches but case-sensitive substitutions. My solution for that:

nnoremap / /\c
nnoremap ? ?\c

With that always when you hit / or ? it will add \c for case-insensitive search.

Answered   2023-09-20 21:00:26

  • Not a bad suggestion, but does it prevent you from using the smartcase option? - anyone
  • Looks like it would since \c overrides smartcase - anyone

Vim have 2 modes

1.edit mode

  1. normal mode( Esc )

Search will work for normal mode

/\c for case sensitive

/\csearch

Answered   2023-09-20 21:00:26

You can set ignorecase by default, run this in shell

echo "set ic" >> ~/.vimrc

Answered   2023-09-20 21:00:26

Note it is a difference where you place modifiers such as "\c" in your expresion:

You can use the \c escape sequence anywhere in the pattern

Regardless from the accepted answers, which states that it is no difference of where to place modyfier in a regex pattern, its looks like it actually does matter.

example text:

asdasdasdasdasd wiktor asdasdasdasd   
adasdasdasd wiktor asdasda ahjkjlkhjkl
asdasd asd asdasdasdasd iuuuu -       
asdjkkkkkkkaopbsdasda                 
wiktor ----(---------------------)--

Match

\c^.*A?.*$
^\c.*A?.*$
^.*\cA?.*$
^.*A\c?.*$

will output: enter image description here

No match

^.\c*A?.*$
^.*A?\c.*$
^.*A?.\c*$
^.*A?.*$\c

will output: enter image description here enter image description here

  • vim -version VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Jun 1 2020 06:42:35) Included patches: 1-869

Answered   2023-09-20 21:00:26

Some important information, if u want to find out more about the commands of vim, as mentioned below u can give a try the following steps :

  • invoke the command "help" follow by a space and then complete the word with TAB key, once u find the right command press return key.
:help ignorecase
  • information like the following will be displayed :

enter image description here

  • you will be able to move forward and backward and also watch the short command, such as the case of "ignorecase" ( 'ic' ). In addition, another short example could be the case of 'smartcase' ('scs' and some more) :

enter image description here

  • In order to leave of the documentation just type ":q" as usual and you will return to "command mode" .
:q

I really hope the information provided would be helpful for someone.

Best regards,

Answered   2023-09-20 21:00:26

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