how to do case insensitive search in vim

Question

I'd like to search a upper case word, for example COPYRIGHT in a file . then I try to do the search like:

/copyright/i

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

Answer 1

You need to use the \c escape sequence. So:

/\ccopyright

Answer 2

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

Answer 3

You can issue the command

:set ignorecase

and after that your searches will be case-insensitive.

Answer 4

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 smartcase
/copyright      " Case insensitive
/Copyright      " Case sensitive
/copyright\C    " Case sensitive
/Copyright\c    " Case insensitive

See:

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

Answer 5

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

nmap <F9> :set ignorecase! ignorecase?